diff --git a/docs/topics/migration-from-PHPExcel.md b/docs/topics/migration-from-PHPExcel.md
index b948eac2..c34fba7f 100644
--- a/docs/topics/migration-from-PHPExcel.md
+++ b/docs/topics/migration-from-PHPExcel.md
@@ -171,3 +171,24 @@ to `\PhpOffice\PhpSpreadsheet::getCoordinates()` and
 `\PhpOffice\PhpSpreadsheet::getCellCollection()` for clarity.
 
 Refer to [the new documentation](./memory_saving.md) to see how to migrate.
+
+## Dropped conditionally returned cell
+
+For all the following methods, it is no more possible to change the type of
+returned value. It always return the Worksheet and never the Cell or Rule:
+
+- Worksheet::setCellValue()
+- Worksheet::setCellValueByColumnAndRow()
+- Worksheet::setCellValueExplicit()
+- Worksheet::setCellValueExplicitByColumnAndRow()
+- Worksheet::addRule()
+
+Migration would be similar to:
+
+``` php
+// Before
+$cell = $worksheet->setCellValue('A1', 'value', true);
+
+// After
+$cell = $worksheet->getCell('A1')->setValue('value');
+```
diff --git a/src/PhpSpreadsheet/CalcEngine/Logger.php b/src/PhpSpreadsheet/CalcEngine/Logger.php
index 9bc97179..ba4b2971 100644
--- a/src/PhpSpreadsheet/CalcEngine/Logger.php
+++ b/src/PhpSpreadsheet/CalcEngine/Logger.php
@@ -74,7 +74,7 @@ class Logger
      *
      * @param bool $pValue
      */
-    public function setWriteDebugLog($pValue = false)
+    public function setWriteDebugLog($pValue)
     {
         $this->writeDebugLog = $pValue;
     }
@@ -94,7 +94,7 @@ class Logger
      *
      * @param bool $pValue
      */
-    public function setEchoDebugLog($pValue = false)
+    public function setEchoDebugLog($pValue)
     {
         $this->echoDebugLog = $pValue;
     }
diff --git a/src/PhpSpreadsheet/Calculation.php b/src/PhpSpreadsheet/Calculation.php
index 2d75f29a..46414a4a 100644
--- a/src/PhpSpreadsheet/Calculation.php
+++ b/src/PhpSpreadsheet/Calculation.php
@@ -2176,7 +2176,7 @@ class Calculation
      *
      * @param bool $pValue
      */
-    public function setCalculationCacheEnabled($pValue = true)
+    public function setCalculationCacheEnabled($pValue)
     {
         $this->calculationCacheEnabled = $pValue;
         $this->clearCalculationCache();
@@ -2245,11 +2245,11 @@ class Calculation
     /**
      * Set the locale code.
      *
-     * @param string $locale The locale to use for formula translation
+     * @param string $locale The locale to use for formula translation, eg: 'en_us'
      *
      * @return bool
      */
-    public function setLocale($locale = 'en_us')
+    public function setLocale($locale)
     {
         //    Identify our locale and language
         $language = $locale = strtolower($locale);
diff --git a/src/PhpSpreadsheet/Calculation/FormulaToken.php b/src/PhpSpreadsheet/Calculation/FormulaToken.php
index ab46f5b1..ff3c8585 100644
--- a/src/PhpSpreadsheet/Calculation/FormulaToken.php
+++ b/src/PhpSpreadsheet/Calculation/FormulaToken.php
@@ -142,11 +142,11 @@ class FormulaToken
     }
 
     /**
-     * Set Token Type.
+     * Set Token Type (represented by TOKEN_TYPE_*).
      *
      * @param string $value
      */
-    public function setTokenType($value = self::TOKEN_TYPE_UNKNOWN)
+    public function setTokenType($value)
     {
         $this->tokenType = $value;
     }
@@ -162,11 +162,11 @@ class FormulaToken
     }
 
     /**
-     * Set Token SubType.
+     * Set Token SubType (represented by TOKEN_SUBTYPE_*).
      *
      * @param string $value
      */
-    public function setTokenSubType($value = self::TOKEN_SUBTYPE_NOTHING)
+    public function setTokenSubType($value)
     {
         $this->tokenSubType = $value;
     }
diff --git a/src/PhpSpreadsheet/Cell.php b/src/PhpSpreadsheet/Cell.php
index e01a473c..102c0d7c 100644
--- a/src/PhpSpreadsheet/Cell.php
+++ b/src/PhpSpreadsheet/Cell.php
@@ -202,7 +202,7 @@ class Cell
      *
      * @return Cell
      */
-    public function setValue($pValue = null)
+    public function setValue($pValue)
     {
         if (!self::getValueBinder()->bindValue($this, $pValue)) {
             throw new Exception('Value could not be bound to cell.');
@@ -215,13 +215,13 @@ class Cell
      * Set the value for a cell, with the explicit data type passed to the method (bypassing any use of the value binder).
      *
      * @param mixed $pValue Value
-     * @param string $pDataType Explicit data type
+     * @param string $pDataType Explicit data type, see Cell\DataType::TYPE_*
      *
      * @throws Exception
      *
      * @return Cell
      */
-    public function setValueExplicit($pValue = null, $pDataType = Cell\DataType::TYPE_STRING)
+    public function setValueExplicit($pValue, $pDataType)
     {
         // set the value according to data type
         switch ($pDataType) {
@@ -311,7 +311,7 @@ class Cell
      *
      * @return Cell
      */
-    public function setCalculatedValue($pValue = null)
+    public function setCalculatedValue($pValue)
     {
         if ($pValue !== null) {
             $this->calculatedValue = (is_numeric($pValue)) ? (float) $pValue : $pValue;
@@ -348,11 +348,11 @@ class Cell
     /**
      * Set cell data type.
      *
-     * @param string $pDataType
+     * @param string $pDataType see Cell\DataType::TYPE_*
      *
      * @return Cell
      */
-    public function setDataType($pDataType = Cell\DataType::TYPE_STRING)
+    public function setDataType($pDataType)
     {
         if ($pDataType == Cell\DataType::TYPE_STRING2) {
             $pDataType = Cell\DataType::TYPE_STRING;
@@ -571,7 +571,7 @@ class Cell
      *
      * @return bool
      */
-    public function isInRange($pRange = 'A1:A1')
+    public function isInRange($pRange)
     {
         list($rangeStart, $rangeEnd) = self::rangeBoundaries($pRange);
 
@@ -587,13 +587,13 @@ class Cell
     /**
      * Coordinate from string.
      *
-     * @param string $pCoordinateString
+     * @param string $pCoordinateString eg: 'A1'
      *
      * @throws Exception
      *
      * @return string[] Array containing column and row (indexes 0 and 1)
      */
-    public static function coordinateFromString($pCoordinateString = 'A1')
+    public static function coordinateFromString($pCoordinateString)
     {
         if (preg_match("/^([$]?[A-Z]{1,3})([$]?\d{1,7})$/", $pCoordinateString, $matches)) {
             return [$matches[1], $matches[2]];
@@ -616,7 +616,7 @@ class Cell
      *
      * @return string Absolute coordinate        e.g. '$A' or '$1' or '$A$1'
      */
-    public static function absoluteReference($pCoordinateString = 'A1')
+    public static function absoluteReference($pCoordinateString)
     {
         if (strpos($pCoordinateString, ':') === false && strpos($pCoordinateString, ',') === false) {
             // Split out any worksheet name from the reference
@@ -651,7 +651,7 @@ class Cell
      *
      * @return string Absolute coordinate        e.g. '$A$1'
      */
-    public static function absoluteCoordinate($pCoordinateString = 'A1')
+    public static function absoluteCoordinate($pCoordinateString)
     {
         if (strpos($pCoordinateString, ':') === false && strpos($pCoordinateString, ',') === false) {
             // Split out any worksheet name from the coordinate
@@ -684,7 +684,7 @@ class Cell
      *                                e.g. array('B4','D9') or array(array('B4','D9'),array('H2','O11'))
      *                                        or array('B4')
      */
-    public static function splitRange($pRange = 'A1:A1')
+    public static function splitRange($pRange)
     {
         // Ensure $pRange is a valid range
         if (empty($pRange)) {
@@ -735,7 +735,7 @@ class Cell
      * @return array Range coordinates array(Start Cell, End Cell)
      *                    where Start Cell and End Cell are arrays (Column Number, Row Number)
      */
-    public static function rangeBoundaries($pRange = 'A1:A1')
+    public static function rangeBoundaries($pRange)
     {
         // Ensure $pRange is a valid range
         if (empty($pRange)) {
@@ -770,7 +770,7 @@ class Cell
      *
      * @return array Range dimension (width, height)
      */
-    public static function rangeDimension($pRange = 'A1:A1')
+    public static function rangeDimension($pRange)
     {
         // Calculate range outer borders
         list($rangeStart, $rangeEnd) = self::rangeBoundaries($pRange);
@@ -786,7 +786,7 @@ class Cell
      * @return array Range coordinates array(Start Cell, End Cell)
      *                    where Start Cell and End Cell are arrays (Column ID, Row Number)
      */
-    public static function getRangeBoundaries($pRange = 'A1:A1')
+    public static function getRangeBoundaries($pRange)
     {
         // Ensure $pRange is a valid range
         if (empty($pRange)) {
@@ -809,11 +809,11 @@ class Cell
     /**
      * Column index from string.
      *
-     * @param string $pString
+     * @param string $pString eg 'A'
      *
      * @return int Column index (base 1 !!!)
      */
-    public static function columnIndexFromString($pString = 'A')
+    public static function columnIndexFromString($pString)
     {
         //    Using a lookup cache adds a slight memory overhead, but boosts speed
         //    caching using a static within the method is faster than a class static,
@@ -856,11 +856,11 @@ class Cell
     /**
      * String from columnindex.
      *
-     * @param int $pColumnIndex Column index (base 0 !!!)
+     * @param int $pColumnIndex Column index (A = 0)
      *
      * @return string
      */
-    public static function stringFromColumnIndex($pColumnIndex = 0)
+    public static function stringFromColumnIndex($pColumnIndex)
     {
         //    Using a lookup cache adds a slight memory overhead, but boosts speed
         //    caching using a static within the method is faster than a class static,
@@ -891,7 +891,7 @@ class Cell
      *
      * @return array Array containing single cell references
      */
-    public static function extractAllCellReferencesInRange($pRange = 'A1')
+    public static function extractAllCellReferencesInRange($pRange)
     {
         // Returnvalue
         $returnValue = [];
@@ -1031,7 +1031,7 @@ class Cell
      *
      * @return Cell
      */
-    public function setXfIndex($pValue = 0)
+    public function setXfIndex($pValue)
     {
         $this->xfIndex = $pValue;
 
diff --git a/src/PhpSpreadsheet/Cell/DataType.php b/src/PhpSpreadsheet/Cell/DataType.php
index ee2fa6b6..2f41b66c 100644
--- a/src/PhpSpreadsheet/Cell/DataType.php
+++ b/src/PhpSpreadsheet/Cell/DataType.php
@@ -69,7 +69,7 @@ class DataType
      *
      * @return mixed Sanitized value
      */
-    public static function checkString($pValue = null)
+    public static function checkString($pValue)
     {
         if ($pValue instanceof \PhpOffice\PhpSpreadsheet\RichText) {
             // TODO: Sanitize Rich-Text string (max. character count is 32,767)
@@ -93,7 +93,7 @@ class DataType
      *
      * @return string Sanitized value
      */
-    public static function checkErrorCode($pValue = null)
+    public static function checkErrorCode($pValue)
     {
         $pValue = (string) $pValue;
 
diff --git a/src/PhpSpreadsheet/Cell/DataValidation.php b/src/PhpSpreadsheet/Cell/DataValidation.php
index 7d710164..ae138bde 100644
--- a/src/PhpSpreadsheet/Cell/DataValidation.php
+++ b/src/PhpSpreadsheet/Cell/DataValidation.php
@@ -166,7 +166,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setFormula1($value = '')
+    public function setFormula1($value)
     {
         $this->formula1 = $value;
 
@@ -190,7 +190,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setFormula2($value = '')
+    public function setFormula2($value)
     {
         $this->formula2 = $value;
 
@@ -214,7 +214,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setType($value = self::TYPE_NONE)
+    public function setType($value)
     {
         $this->type = $value;
 
@@ -234,11 +234,11 @@ class DataValidation
     /**
      * Set Error style.
      *
-     * @param string $value
+     * @param string $value see self::STYLE_*
      *
      * @return DataValidation
      */
-    public function setErrorStyle($value = self::STYLE_STOP)
+    public function setErrorStyle($value)
     {
         $this->errorStyle = $value;
 
@@ -262,7 +262,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setOperator($value = '')
+    public function setOperator($value)
     {
         $this->operator = $value;
 
@@ -286,7 +286,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setAllowBlank($value = false)
+    public function setAllowBlank($value)
     {
         $this->allowBlank = $value;
 
@@ -310,7 +310,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setShowDropDown($value = false)
+    public function setShowDropDown($value)
     {
         $this->showDropDown = $value;
 
@@ -334,7 +334,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setShowInputMessage($value = false)
+    public function setShowInputMessage($value)
     {
         $this->showInputMessage = $value;
 
@@ -358,7 +358,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setShowErrorMessage($value = false)
+    public function setShowErrorMessage($value)
     {
         $this->showErrorMessage = $value;
 
@@ -382,7 +382,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setErrorTitle($value = '')
+    public function setErrorTitle($value)
     {
         $this->errorTitle = $value;
 
@@ -406,7 +406,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setError($value = '')
+    public function setError($value)
     {
         $this->error = $value;
 
@@ -430,7 +430,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setPromptTitle($value = '')
+    public function setPromptTitle($value)
     {
         $this->promptTitle = $value;
 
@@ -454,7 +454,7 @@ class DataValidation
      *
      * @return DataValidation
      */
-    public function setPrompt($value = '')
+    public function setPrompt($value)
     {
         $this->prompt = $value;
 
diff --git a/src/PhpSpreadsheet/Cell/DefaultValueBinder.php b/src/PhpSpreadsheet/Cell/DefaultValueBinder.php
index 461c96e6..f9e7729f 100644
--- a/src/PhpSpreadsheet/Cell/DefaultValueBinder.php
+++ b/src/PhpSpreadsheet/Cell/DefaultValueBinder.php
@@ -62,7 +62,7 @@ class DefaultValueBinder implements IValueBinder
      *
      * @return string
      */
-    public static function dataTypeForValue($pValue = null)
+    public static function dataTypeForValue($pValue)
     {
         // Match the value against a few data types
         if ($pValue === null) {
diff --git a/src/PhpSpreadsheet/Cell/Hyperlink.php b/src/PhpSpreadsheet/Cell/Hyperlink.php
index 0ec811b7..6065357d 100644
--- a/src/PhpSpreadsheet/Cell/Hyperlink.php
+++ b/src/PhpSpreadsheet/Cell/Hyperlink.php
@@ -70,7 +70,7 @@ class Hyperlink
      *
      * @return Hyperlink
      */
-    public function setUrl($value = '')
+    public function setUrl($value)
     {
         $this->url = $value;
 
@@ -94,7 +94,7 @@ class Hyperlink
      *
      * @return Hyperlink
      */
-    public function setTooltip($value = '')
+    public function setTooltip($value)
     {
         $this->tooltip = $value;
 
diff --git a/src/PhpSpreadsheet/Chart.php b/src/PhpSpreadsheet/Chart.php
index 17530463..ea31112a 100644
--- a/src/PhpSpreadsheet/Chart.php
+++ b/src/PhpSpreadsheet/Chart.php
@@ -341,7 +341,7 @@ class Chart
      *
      * @return Chart
      */
-    public function setPlotVisibleOnly($plotVisibleOnly = true)
+    public function setPlotVisibleOnly($plotVisibleOnly)
     {
         $this->plotVisibleOnly = $plotVisibleOnly;
 
@@ -365,7 +365,7 @@ class Chart
      *
      * @return Chart
      */
-    public function setDisplayBlanksAs($displayBlanksAs = '0')
+    public function setDisplayBlanksAs($displayBlanksAs)
     {
         $this->displayBlanksAs = $displayBlanksAs;
     }
@@ -494,11 +494,12 @@ class Chart
      *
      * @return Chart
      */
-    public function setTopLeftOffset($xOffset = null, $yOffset = null)
+    public function setTopLeftOffset($xOffset, $yOffset)
     {
         if (!is_null($xOffset)) {
             $this->setTopLeftXOffset($xOffset);
         }
+
         if (!is_null($yOffset)) {
             $this->setTopLeftYOffset($yOffset);
         }
@@ -604,11 +605,12 @@ class Chart
      *
      * @return Chart
      */
-    public function setBottomRightOffset($xOffset = null, $yOffset = null)
+    public function setBottomRightOffset($xOffset, $yOffset)
     {
         if (!is_null($xOffset)) {
             $this->setBottomRightXOffset($xOffset);
         }
+
         if (!is_null($yOffset)) {
             $this->setBottomRightYOffset($yOffset);
         }
diff --git a/src/PhpSpreadsheet/Chart/DataSeries.php b/src/PhpSpreadsheet/Chart/DataSeries.php
index 6dc90760..092736a6 100644
--- a/src/PhpSpreadsheet/Chart/DataSeries.php
+++ b/src/PhpSpreadsheet/Chart/DataSeries.php
@@ -178,7 +178,7 @@ class DataSeries
      *
      * @return DataSeries
      */
-    public function setPlotType($plotType = '')
+    public function setPlotType($plotType)
     {
         $this->plotType = $plotType;
 
@@ -202,7 +202,7 @@ class DataSeries
      *
      * @return DataSeries
      */
-    public function setPlotGrouping($groupingType = null)
+    public function setPlotGrouping($groupingType)
     {
         $this->plotGrouping = $groupingType;
 
@@ -226,7 +226,7 @@ class DataSeries
      *
      * @return DataSeries
      */
-    public function setPlotDirection($plotDirection = null)
+    public function setPlotDirection($plotDirection)
     {
         $this->plotDirection = $plotDirection;
 
@@ -318,7 +318,7 @@ class DataSeries
      *
      * @return DataSeries
      */
-    public function setPlotStyle($plotStyle = null)
+    public function setPlotStyle($plotStyle)
     {
         $this->plotStyle = $plotStyle;
 
@@ -381,7 +381,7 @@ class DataSeries
      *
      * @return DataSeries
      */
-    public function setSmoothLine($smoothLine = true)
+    public function setSmoothLine($smoothLine)
     {
         $this->smoothLine = $smoothLine;
 
diff --git a/src/PhpSpreadsheet/Chart/DataSeriesValues.php b/src/PhpSpreadsheet/Chart/DataSeriesValues.php
index d1e92df1..82813400 100644
--- a/src/PhpSpreadsheet/Chart/DataSeriesValues.php
+++ b/src/PhpSpreadsheet/Chart/DataSeriesValues.php
@@ -120,7 +120,7 @@ class DataSeriesValues
      *
      * @return DataSeriesValues
      */
-    public function setDataType($dataType = self::DATASERIES_TYPE_NUMBER)
+    public function setDataType($dataType)
     {
         if (!in_array($dataType, self::$dataTypeValues)) {
             throw new Exception('Invalid datatype for chart data series values');
@@ -144,18 +144,13 @@ class DataSeriesValues
      * Set Series Data Source (formula).
      *
      * @param string $dataSource
-     * @param mixed $refreshDataValues
      *
      * @return DataSeriesValues
      */
-    public function setDataSource($dataSource = null, $refreshDataValues = true)
+    public function setDataSource($dataSource)
     {
         $this->dataSource = $dataSource;
 
-        if ($refreshDataValues) {
-            //    TO DO
-        }
-
         return $this;
     }
 
@@ -176,7 +171,7 @@ class DataSeriesValues
      *
      * @return DataSeriesValues
      */
-    public function setPointMarker($marker = null)
+    public function setPointMarker($marker)
     {
         $this->pointMarker = $marker;
 
@@ -200,7 +195,7 @@ class DataSeriesValues
      *
      * @return DataSeriesValues
      */
-    public function setFormatCode($formatCode = null)
+    public function setFormatCode($formatCode)
     {
         $this->formatCode = $formatCode;
 
@@ -277,29 +272,17 @@ class DataSeriesValues
      * Set Series Data Values.
      *
      * @param array $dataValues
-     * @param bool $refreshDataSource
-     *                    TRUE - refresh the value of dataSource based on the values of $dataValues
-     *                    FALSE - don't change the value of dataSource
      *
      * @return DataSeriesValues
      */
-    public function setDataValues($dataValues = [], $refreshDataSource = true)
+    public function setDataValues($dataValues)
     {
         $this->dataValues = \PhpOffice\PhpSpreadsheet\Calculation\Functions::flattenArray($dataValues);
         $this->pointCount = count($dataValues);
 
-        if ($refreshDataSource) {
-            //    TO DO
-        }
-
         return $this;
     }
 
-    private function stripNulls($var)
-    {
-        return $var !== null;
-    }
-
     public function refresh(\PhpOffice\PhpSpreadsheet\Worksheet $worksheet, $flatten = true)
     {
         if ($this->dataSource !== null) {
diff --git a/src/PhpSpreadsheet/Chart/Layout.php b/src/PhpSpreadsheet/Chart/Layout.php
index 98e5e6f6..9480d691 100644
--- a/src/PhpSpreadsheet/Chart/Layout.php
+++ b/src/PhpSpreadsheet/Chart/Layout.php
@@ -133,9 +133,9 @@ class Layout
     /**
      * Create a new Layout.
      *
-     * @param mixed $layout
+     * @param array $layout
      */
-    public function __construct($layout = [])
+    public function __construct(array $layout = [])
     {
         if (isset($layout['layoutTarget'])) {
             $this->layoutTarget = $layout['layoutTarget'];
diff --git a/src/PhpSpreadsheet/Chart/Legend.php b/src/PhpSpreadsheet/Chart/Legend.php
index c472cd8f..dea8610d 100644
--- a/src/PhpSpreadsheet/Chart/Legend.php
+++ b/src/PhpSpreadsheet/Chart/Legend.php
@@ -96,9 +96,9 @@ class Legend
     /**
      * Get legend position using an excel string value.
      *
-     * @param string $position
+     * @param string $position see self::POSITION_*
      */
-    public function setPosition($position = self::POSITION_RIGHT)
+    public function setPosition($position)
     {
         if (!in_array($position, self::$positionXLref)) {
             return false;
@@ -112,7 +112,7 @@ class Legend
     /**
      * Get legend position as an Excel internal numeric value.
      *
-     * @return number
+     * @return int
      */
     public function getPositionXL()
     {
@@ -122,9 +122,9 @@ class Legend
     /**
      * Set legend position using an Excel internal numeric value.
      *
-     * @param number $positionXL
+     * @param int $positionXL see self::XL_LEGEND_POSITION_*
      */
-    public function setPositionXL($positionXL = self::XL_LEGEND_POSITION_RIGHT)
+    public function setPositionXL($positionXL)
     {
         if (!isset(self::$positionXLref[$positionXL])) {
             return false;
@@ -152,7 +152,7 @@ class Legend
      *
      * @return bool
      */
-    public function setOverlay($overlay = false)
+    public function setOverlay($overlay)
     {
         if (!is_bool($overlay)) {
             return false;
diff --git a/src/PhpSpreadsheet/Chart/PlotArea.php b/src/PhpSpreadsheet/Chart/PlotArea.php
index afcced96..f3c4d9f2 100644
--- a/src/PhpSpreadsheet/Chart/PlotArea.php
+++ b/src/PhpSpreadsheet/Chart/PlotArea.php
@@ -45,7 +45,7 @@ class PlotArea
      *
      * @param mixed $plotSeries
      */
-    public function __construct(Layout $layout = null, $plotSeries = [])
+    public function __construct(Layout $layout = null, array $plotSeries = [])
     {
         $this->layout = $layout;
         $this->plotSeries = $plotSeries;
@@ -116,7 +116,7 @@ class PlotArea
      *
      * @return PlotArea
      */
-    public function setPlotSeries($plotSeries = [])
+    public function setPlotSeries(array $plotSeries)
     {
         $this->plotSeries = $plotSeries;
 
diff --git a/src/PhpSpreadsheet/Chart/Title.php b/src/PhpSpreadsheet/Chart/Title.php
index 753e63e8..491f5ecb 100644
--- a/src/PhpSpreadsheet/Chart/Title.php
+++ b/src/PhpSpreadsheet/Chart/Title.php
@@ -68,7 +68,7 @@ class Title
      *
      * @return Title
      */
-    public function setCaption($caption = null)
+    public function setCaption($caption)
     {
         $this->caption = $caption;
 
diff --git a/src/PhpSpreadsheet/Comment.php b/src/PhpSpreadsheet/Comment.php
index f04f3ce6..28bce22c 100644
--- a/src/PhpSpreadsheet/Comment.php
+++ b/src/PhpSpreadsheet/Comment.php
@@ -116,13 +116,13 @@ class Comment implements IComparable
     /**
      * Set Author.
      *
-     * @param string $pValue
+     * @param string $author
      *
      * @return Comment
      */
-    public function setAuthor($pValue = '')
+    public function setAuthor($author)
     {
-        $this->author = $pValue;
+        $this->author = $author;
 
         return $this;
     }
@@ -164,13 +164,13 @@ class Comment implements IComparable
     /**
      * Set comment width (CSS style, i.e. XXpx or YYpt).
      *
-     * @param string $value
+     * @param string $width
      *
      * @return Comment
      */
-    public function setWidth($value = '96pt')
+    public function setWidth($width)
     {
-        $this->width = $value;
+        $this->width = $width;
 
         return $this;
     }
@@ -192,7 +192,7 @@ class Comment implements IComparable
      *
      * @return Comment
      */
-    public function setHeight($value = '55.5pt')
+    public function setHeight($value)
     {
         $this->height = $value;
 
@@ -216,7 +216,7 @@ class Comment implements IComparable
      *
      * @return Comment
      */
-    public function setMarginLeft($value = '59.25pt')
+    public function setMarginLeft($value)
     {
         $this->marginLeft = $value;
 
@@ -240,7 +240,7 @@ class Comment implements IComparable
      *
      * @return Comment
      */
-    public function setMarginTop($value = '1.5pt')
+    public function setMarginTop($value)
     {
         $this->marginTop = $value;
 
@@ -264,7 +264,7 @@ class Comment implements IComparable
      *
      * @return Comment
      */
-    public function setVisible($value = false)
+    public function setVisible($value)
     {
         $this->visible = $value;
 
@@ -284,13 +284,13 @@ class Comment implements IComparable
     /**
      * Set Alignment.
      *
-     * @param string $pValue
+     * @param string $alignment see Style\Alignment::HORIZONTAL_*
      *
      * @return Comment
      */
-    public function setAlignment($pValue = Style\Alignment::HORIZONTAL_GENERAL)
+    public function setAlignment($alignment)
     {
-        $this->alignment = $pValue;
+        $this->alignment = $alignment;
 
         return $this;
     }
diff --git a/src/PhpSpreadsheet/Document/Properties.php b/src/PhpSpreadsheet/Document/Properties.php
index d0705dc8..da00fd2c 100644
--- a/src/PhpSpreadsheet/Document/Properties.php
+++ b/src/PhpSpreadsheet/Document/Properties.php
@@ -142,13 +142,13 @@ class Properties
     /**
      * Set Creator.
      *
-     * @param string $pValue
+     * @param string $creator
      *
      * @return Properties
      */
-    public function setCreator($pValue = '')
+    public function setCreator($creator)
     {
-        $this->creator = $pValue;
+        $this->creator = $creator;
 
         return $this;
     }
@@ -170,7 +170,7 @@ class Properties
      *
      * @return Properties
      */
-    public function setLastModifiedBy($pValue = '')
+    public function setLastModifiedBy($pValue)
     {
         $this->lastModifiedBy = $pValue;
 
@@ -194,7 +194,7 @@ class Properties
      *
      * @return Properties
      */
-    public function setCreated($pValue = null)
+    public function setCreated($pValue)
     {
         if ($pValue === null) {
             $pValue = time();
@@ -228,7 +228,7 @@ class Properties
      *
      * @return Properties
      */
-    public function setModified($pValue = null)
+    public function setModified($pValue)
     {
         if ($pValue === null) {
             $pValue = time();
@@ -258,13 +258,13 @@ class Properties
     /**
      * Set Title.
      *
-     * @param string $pValue
+     * @param string $title
      *
      * @return Properties
      */
-    public function setTitle($pValue = '')
+    public function setTitle($title)
     {
-        $this->title = $pValue;
+        $this->title = $title;
 
         return $this;
     }
@@ -282,13 +282,13 @@ class Properties
     /**
      * Set Description.
      *
-     * @param string $pValue
+     * @param string $description
      *
      * @return Properties
      */
-    public function setDescription($pValue = '')
+    public function setDescription($description)
     {
-        $this->description = $pValue;
+        $this->description = $description;
 
         return $this;
     }
@@ -306,13 +306,13 @@ class Properties
     /**
      * Set Subject.
      *
-     * @param string $pValue
+     * @param string $subject
      *
      * @return Properties
      */
-    public function setSubject($pValue = '')
+    public function setSubject($subject)
     {
-        $this->subject = $pValue;
+        $this->subject = $subject;
 
         return $this;
     }
@@ -330,13 +330,13 @@ class Properties
     /**
      * Set Keywords.
      *
-     * @param string $pValue
+     * @param string $keywords
      *
      * @return Properties
      */
-    public function setKeywords($pValue = '')
+    public function setKeywords($keywords)
     {
-        $this->keywords = $pValue;
+        $this->keywords = $keywords;
 
         return $this;
     }
@@ -354,13 +354,13 @@ class Properties
     /**
      * Set Category.
      *
-     * @param string $pValue
+     * @param string $category
      *
      * @return Properties
      */
-    public function setCategory($pValue = '')
+    public function setCategory($category)
     {
-        $this->category = $pValue;
+        $this->category = $category;
 
         return $this;
     }
@@ -378,13 +378,13 @@ class Properties
     /**
      * Set Company.
      *
-     * @param string $pValue
+     * @param string $company
      *
      * @return Properties
      */
-    public function setCompany($pValue = '')
+    public function setCompany($company)
     {
-        $this->company = $pValue;
+        $this->company = $company;
 
         return $this;
     }
@@ -402,13 +402,13 @@ class Properties
     /**
      * Set Manager.
      *
-     * @param string $pValue
+     * @param string $manager
      *
      * @return Properties
      */
-    public function setManager($pValue = '')
+    public function setManager($manager)
     {
-        $this->manager = $pValue;
+        $this->manager = $manager;
 
         return $this;
     }
diff --git a/src/PhpSpreadsheet/Document/Security.php b/src/PhpSpreadsheet/Document/Security.php
index 380f7265..6bb99b97 100644
--- a/src/PhpSpreadsheet/Document/Security.php
+++ b/src/PhpSpreadsheet/Document/Security.php
@@ -97,7 +97,7 @@ class Security
      *
      * @return Security
      */
-    public function setLockRevision($pValue = false)
+    public function setLockRevision($pValue)
     {
         $this->lockRevision = $pValue;
 
@@ -121,7 +121,7 @@ class Security
      *
      * @return Security
      */
-    public function setLockStructure($pValue = false)
+    public function setLockStructure($pValue)
     {
         $this->lockStructure = $pValue;
 
@@ -145,7 +145,7 @@ class Security
      *
      * @return Security
      */
-    public function setLockWindows($pValue = false)
+    public function setLockWindows($pValue)
     {
         $this->lockWindows = $pValue;
 
@@ -170,7 +170,7 @@ class Security
      *
      * @return Security
      */
-    public function setRevisionsPassword($pValue = '', $pAlreadyHashed = false)
+    public function setRevisionsPassword($pValue, $pAlreadyHashed = false)
     {
         if (!$pAlreadyHashed) {
             $pValue = \PhpOffice\PhpSpreadsheet\Shared\PasswordHasher::hashPassword($pValue);
@@ -198,7 +198,7 @@ class Security
      *
      * @return Security
      */
-    public function setWorkbookPassword($pValue = '', $pAlreadyHashed = false)
+    public function setWorkbookPassword($pValue, $pAlreadyHashed = false)
     {
         if (!$pAlreadyHashed) {
             $pValue = \PhpOffice\PhpSpreadsheet\Shared\PasswordHasher::hashPassword($pValue);
diff --git a/src/PhpSpreadsheet/HashTable.php b/src/PhpSpreadsheet/HashTable.php
index fededf17..cda8c0d5 100644
--- a/src/PhpSpreadsheet/HashTable.php
+++ b/src/PhpSpreadsheet/HashTable.php
@@ -62,13 +62,11 @@ class HashTable
      *
      * @throws Exception
      */
-    public function addFromSource($pSource = null)
+    public function addFromSource(array $pSource = null)
     {
         // Check if an array was passed
         if ($pSource == null) {
             return;
-        } elseif (!is_array($pSource)) {
-            throw new Exception('Invalid array parameter passed.');
         }
 
         foreach ($pSource as $item) {
@@ -145,7 +143,7 @@ class HashTable
      *
      * @return int Index
      */
-    public function getIndexForHashCode($pHashCode = '')
+    public function getIndexForHashCode($pHashCode)
     {
         return array_search($pHashCode, $this->keyMap);
     }
@@ -157,7 +155,7 @@ class HashTable
      *
      * @return IComparable
      */
-    public function getByIndex($pIndex = 0)
+    public function getByIndex($pIndex)
     {
         if (isset($this->keyMap[$pIndex])) {
             return $this->getByHashCode($this->keyMap[$pIndex]);
@@ -173,7 +171,7 @@ class HashTable
      *
      * @return IComparable
      */
-    public function getByHashCode($pHashCode = '')
+    public function getByHashCode($pHashCode)
     {
         if (isset($this->items[$pHashCode])) {
             return $this->items[$pHashCode];
diff --git a/src/PhpSpreadsheet/IOFactory.php b/src/PhpSpreadsheet/IOFactory.php
index 949cc87d..c59530a9 100644
--- a/src/PhpSpreadsheet/IOFactory.php
+++ b/src/PhpSpreadsheet/IOFactory.php
@@ -102,7 +102,7 @@ class IOFactory
      * @param string $location Example: PhpSpreadsheet/Writer/{0}.php
      * @param string $classname Example: Writer\{0}
      */
-    public static function addSearchLocation($type = '', $location = '', $classname = '')
+    public static function addSearchLocation($type, $location, $classname)
     {
         self::$searchLocations[] = ['type' => $type, 'path' => $location, 'class' => $classname];
     }
@@ -151,7 +151,7 @@ class IOFactory
      *
      * @return Reader\IReader
      */
-    public static function createReader($readerType = '')
+    public static function createReader($readerType)
     {
         // Search type
         $searchType = 'IReader';
diff --git a/src/PhpSpreadsheet/NamedRange.php b/src/PhpSpreadsheet/NamedRange.php
index fffe7ee9..35942ea5 100644
--- a/src/PhpSpreadsheet/NamedRange.php
+++ b/src/PhpSpreadsheet/NamedRange.php
@@ -104,7 +104,7 @@ class NamedRange
      *
      * @return NamedRange
      */
-    public function setName($value = null)
+    public function setName($value)
     {
         if ($value !== null) {
             // Old title
@@ -171,7 +171,7 @@ class NamedRange
      *
      * @return NamedRange
      */
-    public function setRange($value = null)
+    public function setRange($value)
     {
         if ($value !== null) {
             $this->range = $value;
@@ -197,7 +197,7 @@ class NamedRange
      *
      * @return NamedRange
      */
-    public function setLocalOnly($value = false)
+    public function setLocalOnly($value)
     {
         $this->localOnly = $value;
         $this->scope = $value ? $this->worksheet : null;
diff --git a/src/PhpSpreadsheet/Reader/BaseReader.php b/src/PhpSpreadsheet/Reader/BaseReader.php
index dd8d0769..5ef189f4 100644
--- a/src/PhpSpreadsheet/Reader/BaseReader.php
+++ b/src/PhpSpreadsheet/Reader/BaseReader.php
@@ -92,7 +92,7 @@ abstract class BaseReader implements IReader
      *
      * @return IReader
      */
-    public function setReadDataOnly($pValue = false)
+    public function setReadDataOnly($pValue)
     {
         $this->readDataOnly = (bool) $pValue;
 
@@ -120,7 +120,7 @@ abstract class BaseReader implements IReader
      *
      * @return IReader
      */
-    public function setReadEmptyCells($pValue = true)
+    public function setReadEmptyCells($pValue)
     {
         $this->readEmptyCells = (bool) $pValue;
 
@@ -150,7 +150,7 @@ abstract class BaseReader implements IReader
      *
      * @return IReader
      */
-    public function setIncludeCharts($pValue = false)
+    public function setIncludeCharts($pValue)
     {
         $this->includeCharts = (bool) $pValue;
 
@@ -178,7 +178,7 @@ abstract class BaseReader implements IReader
      *
      * @return IReader
      */
-    public function setLoadSheetsOnly($value = null)
+    public function setLoadSheetsOnly($value)
     {
         if ($value === null) {
             return $this->setLoadAllSheets();
diff --git a/src/PhpSpreadsheet/Reader/Csv.php b/src/PhpSpreadsheet/Reader/Csv.php
index 5c623fa5..29876f77 100644
--- a/src/PhpSpreadsheet/Reader/Csv.php
+++ b/src/PhpSpreadsheet/Reader/Csv.php
@@ -81,9 +81,9 @@ class Csv extends BaseReader implements IReader
     /**
      * Set input encoding.
      *
-     * @param string $pValue Input encoding
+     * @param string $pValue Input encoding, eg: 'UTF-8'
      */
-    public function setInputEncoding($pValue = 'UTF-8')
+    public function setInputEncoding($pValue)
     {
         $this->inputEncoding = $pValue;
 
@@ -294,13 +294,13 @@ class Csv extends BaseReader implements IReader
     /**
      * Set delimiter.
      *
-     * @param string $pValue Delimiter, defaults to ,
+     * @param string $delimiter Delimiter, eg: ','
      *
      * @return CSV
      */
-    public function setDelimiter($pValue = ',')
+    public function setDelimiter($delimiter)
     {
-        $this->delimiter = $pValue;
+        $this->delimiter = $delimiter;
 
         return $this;
     }
@@ -318,16 +318,16 @@ class Csv extends BaseReader implements IReader
     /**
      * Set enclosure.
      *
-     * @param string $pValue Enclosure, defaults to "
+     * @param string $enclosure Enclosure, defaults to "
      *
      * @return CSV
      */
-    public function setEnclosure($pValue = '"')
+    public function setEnclosure($enclosure)
     {
-        if ($pValue == '') {
-            $pValue = '"';
+        if ($enclosure == '') {
+            $enclosure = '"';
         }
-        $this->enclosure = $pValue;
+        $this->enclosure = $enclosure;
 
         return $this;
     }
@@ -349,7 +349,7 @@ class Csv extends BaseReader implements IReader
      *
      * @return CSV
      */
-    public function setSheetIndex($pValue = 0)
+    public function setSheetIndex($pValue)
     {
         $this->sheetIndex = $pValue;
 
@@ -361,7 +361,7 @@ class Csv extends BaseReader implements IReader
      *
      * @param bool $contiguous
      */
-    public function setContiguous($contiguous = false)
+    public function setContiguous($contiguous)
     {
         $this->contiguous = (bool) $contiguous;
         if (!$contiguous) {
diff --git a/src/PhpSpreadsheet/Reader/Gnumeric.php b/src/PhpSpreadsheet/Reader/Gnumeric.php
index c31ecd15..c6418704 100644
--- a/src/PhpSpreadsheet/Reader/Gnumeric.php
+++ b/src/PhpSpreadsheet/Reader/Gnumeric.php
@@ -804,7 +804,7 @@ class Gnumeric extends BaseReader implements IReader
         return $styleArray;
     }
 
-    private function parseRichText($is = '')
+    private function parseRichText($is)
     {
         $value = new \PhpOffice\PhpSpreadsheet\RichText();
         $value->createText($is);
diff --git a/src/PhpSpreadsheet/Reader/Html.php b/src/PhpSpreadsheet/Reader/Html.php
index 95fccc61..2f0aa473 100644
--- a/src/PhpSpreadsheet/Reader/Html.php
+++ b/src/PhpSpreadsheet/Reader/Html.php
@@ -208,9 +208,9 @@ class Html extends BaseReader implements IReader
     /**
      * Set input encoding.
      *
-     * @param string $pValue Input encoding
+     * @param string $pValue Input encoding, eg: 'ANSI'
      */
-    public function setInputEncoding($pValue = 'ANSI')
+    public function setInputEncoding($pValue)
     {
         $this->inputEncoding = $pValue;
 
@@ -263,7 +263,7 @@ class Html extends BaseReader implements IReader
                 //    Only actually write it if there's content in the string
                 //    Write to worksheet to be done here...
                 //    ... we return the cell so we can mess about with styles more easily
-                $sheet->setCellValue($column . $row, $cellContent, true);
+                $sheet->setCellValue($column . $row, $cellContent);
                 $this->dataArray[$row][$column] = $cellContent;
             }
         } else {
@@ -556,7 +556,7 @@ class Html extends BaseReader implements IReader
      *
      * @return HTML
      */
-    public function setSheetIndex($pValue = 0)
+    public function setSheetIndex($pValue)
     {
         $this->sheetIndex = $pValue;
 
diff --git a/src/PhpSpreadsheet/Reader/Ods.php b/src/PhpSpreadsheet/Reader/Ods.php
index 075b4e52..ac629aca 100644
--- a/src/PhpSpreadsheet/Reader/Ods.php
+++ b/src/PhpSpreadsheet/Reader/Ods.php
@@ -797,7 +797,7 @@ class Ods extends BaseReader implements IReader
      *
      * @return \PhpOffice\PhpSpreadsheet\RichText
      */
-    private function parseRichText($is = '')
+    private function parseRichText($is)
     {
         $value = new \PhpOffice\PhpSpreadsheet\RichText();
         $value->createText($is);
diff --git a/src/PhpSpreadsheet/Reader/Slk.php b/src/PhpSpreadsheet/Reader/Slk.php
index 6e422fb6..dbe2cd0f 100644
--- a/src/PhpSpreadsheet/Reader/Slk.php
+++ b/src/PhpSpreadsheet/Reader/Slk.php
@@ -99,9 +99,9 @@ class Slk extends BaseReader implements IReader
     /**
      * Set input encoding.
      *
-     * @param string $pValue Input encoding
+     * @param string $pValue Input encoding, eg: 'ANSI'
      */
-    public function setInputEncoding($pValue = 'ANSI')
+    public function setInputEncoding($pValue)
     {
         $this->inputEncoding = $pValue;
 
@@ -474,7 +474,7 @@ class Slk extends BaseReader implements IReader
      *
      * @return SYLK
      */
-    public function setSheetIndex($pValue = 0)
+    public function setSheetIndex($pValue)
     {
         $this->sheetIndex = $pValue;
 
diff --git a/src/PhpSpreadsheet/Reader/Xls.php b/src/PhpSpreadsheet/Reader/Xls.php
index af6def07..801b27d7 100644
--- a/src/PhpSpreadsheet/Reader/Xls.php
+++ b/src/PhpSpreadsheet/Reader/Xls.php
@@ -7465,7 +7465,7 @@ class Xls extends BaseReader implements IReader
         return ord($data[$pos]) | (ord($data[$pos + 1]) << 8) | (ord($data[$pos + 2]) << 16) | $_ord_24;
     }
 
-    private function parseRichText($is = '')
+    private function parseRichText($is)
     {
         $value = new \PhpOffice\PhpSpreadsheet\RichText();
         $value->createText($is);
diff --git a/src/PhpSpreadsheet/Reader/Xlsx.php b/src/PhpSpreadsheet/Reader/Xlsx.php
index 5d582e25..a0e98187 100644
--- a/src/PhpSpreadsheet/Reader/Xlsx.php
+++ b/src/PhpSpreadsheet/Reader/Xlsx.php
@@ -2034,7 +2034,7 @@ class Xlsx extends BaseReader implements IReader
      *
      * @return RichText
      */
-    private function parseRichText($is = null)
+    private function parseRichText($is)
     {
         $value = new RichText();
 
@@ -2179,7 +2179,7 @@ class Xlsx extends BaseReader implements IReader
         return $style;
     }
 
-    private static function boolean($value = null)
+    private static function boolean($value)
     {
         if (is_object($value)) {
             $value = (string) $value;
diff --git a/src/PhpSpreadsheet/Reader/Xlsx/Chart.php b/src/PhpSpreadsheet/Reader/Xlsx/Chart.php
index af96c998..48564d6d 100644
--- a/src/PhpSpreadsheet/Reader/Xlsx/Chart.php
+++ b/src/PhpSpreadsheet/Reader/Xlsx/Chart.php
@@ -88,17 +88,17 @@ class Chart
                                             break;
                                         case 'catAx':
                                             if (isset($chartDetail->title)) {
-                                                $XaxisLabel = self::chartTitle($chartDetail->title->children($namespacesChartMeta['c']), $namespacesChartMeta, 'cat');
+                                                $XaxisLabel = self::chartTitle($chartDetail->title->children($namespacesChartMeta['c']), $namespacesChartMeta);
                                             }
                                             break;
                                         case 'dateAx':
                                             if (isset($chartDetail->title)) {
-                                                $XaxisLabel = self::chartTitle($chartDetail->title->children($namespacesChartMeta['c']), $namespacesChartMeta, 'cat');
+                                                $XaxisLabel = self::chartTitle($chartDetail->title->children($namespacesChartMeta['c']), $namespacesChartMeta);
                                             }
                                             break;
                                         case 'valAx':
                                             if (isset($chartDetail->title)) {
-                                                $YaxisLabel = self::chartTitle($chartDetail->title->children($namespacesChartMeta['c']), $namespacesChartMeta, 'cat');
+                                                $YaxisLabel = self::chartTitle($chartDetail->title->children($namespacesChartMeta['c']), $namespacesChartMeta);
                                             }
                                             break;
                                         case 'barChart':
@@ -176,7 +176,7 @@ class Chart
                                 $dispBlanksAs = self::getAttribute($chartDetails, 'val', 'string');
                                 break;
                             case 'title':
-                                $title = self::chartTitle($chartDetails, $namespacesChartMeta, 'title');
+                                $title = self::chartTitle($chartDetails, $namespacesChartMeta);
                                 break;
                             case 'legend':
                                 $legendPos = 'r';
@@ -206,7 +206,7 @@ class Chart
         return $chart;
     }
 
-    private static function chartTitle($titleDetails, $namespacesChartMeta, $type)
+    private static function chartTitle(\SimpleXMLElement $titleDetails, array $namespacesChartMeta)
     {
         $caption = [];
         $titleLayout = null;
@@ -399,7 +399,7 @@ class Chart
         ];
     }
 
-    private static function parseRichText($titleDetailPart = null)
+    private static function parseRichText(\SimpleXMLElement $titleDetailPart)
     {
         $value = new \PhpOffice\PhpSpreadsheet\RichText();
 
diff --git a/src/PhpSpreadsheet/Reader/Xlsx/Theme.php b/src/PhpSpreadsheet/Reader/Xlsx/Theme.php
index 5767ded8..ba014537 100644
--- a/src/PhpSpreadsheet/Reader/Xlsx/Theme.php
+++ b/src/PhpSpreadsheet/Reader/Xlsx/Theme.php
@@ -96,7 +96,7 @@ class Theme
      *
      * @return string
      */
-    public function getColourByIndex($index = 0)
+    public function getColourByIndex($index)
     {
         if (isset($this->colourMap[$index])) {
             return $this->colourMap[$index];
diff --git a/src/PhpSpreadsheet/Reader/Xml.php b/src/PhpSpreadsheet/Reader/Xml.php
index df0fa48e..00e29808 100644
--- a/src/PhpSpreadsheet/Reader/Xml.php
+++ b/src/PhpSpreadsheet/Reader/Xml.php
@@ -770,7 +770,7 @@ class Xml extends BaseReader implements IReader
         return $string;
     }
 
-    protected function parseRichText($is = '')
+    protected function parseRichText($is)
     {
         $value = new \PhpOffice\PhpSpreadsheet\RichText();
 
diff --git a/src/PhpSpreadsheet/RichText.php b/src/PhpSpreadsheet/RichText.php
index 5f4efe2a..f6d56772 100644
--- a/src/PhpSpreadsheet/RichText.php
+++ b/src/PhpSpreadsheet/RichText.php
@@ -84,7 +84,7 @@ class RichText implements IComparable
      *
      * @return RichText\TextElement
      */
-    public function createText($pText = '')
+    public function createText($pText)
     {
         $objText = new RichText\TextElement($pText);
         $this->addText($objText);
@@ -101,7 +101,7 @@ class RichText implements IComparable
      *
      * @return RichText\Run
      */
-    public function createTextRun($pText = '')
+    public function createTextRun($pText)
     {
         $objText = new RichText\Run($pText);
         $this->addText($objText);
@@ -150,19 +150,15 @@ class RichText implements IComparable
     /**
      * Set Rich Text elements.
      *
-     * @param RichText\ITextElement[] $pElements Array of elements
+     * @param RichText\ITextElement[] $textElements Array of elements
      *
      * @throws Exception
      *
      * @return RichText
      */
-    public function setRichTextElements($pElements = null)
+    public function setRichTextElements(array $textElements)
     {
-        if (is_array($pElements)) {
-            $this->richTextElements = $pElements;
-        } else {
-            throw new Exception("Invalid \PhpOffice\PhpSpreadsheet\RichText\ITextElement[] array passed.");
-        }
+        $this->richTextElements = $textElements;
 
         return $this;
     }
diff --git a/src/PhpSpreadsheet/RichText/ITextElement.php b/src/PhpSpreadsheet/RichText/ITextElement.php
index ae8081da..c69916e1 100644
--- a/src/PhpSpreadsheet/RichText/ITextElement.php
+++ b/src/PhpSpreadsheet/RichText/ITextElement.php
@@ -34,11 +34,11 @@ interface ITextElement
     /**
      * Set text.
      *
-     * @param $pText string Text
+     * @param $text string Text
      *
      * @return ITextElement
      */
-    public function setText($pText = '');
+    public function setText($text);
 
     /**
      * Get font.
diff --git a/src/PhpSpreadsheet/RichText/TextElement.php b/src/PhpSpreadsheet/RichText/TextElement.php
index 4bf405e7..5bc9bfca 100644
--- a/src/PhpSpreadsheet/RichText/TextElement.php
+++ b/src/PhpSpreadsheet/RichText/TextElement.php
@@ -55,13 +55,13 @@ class TextElement implements ITextElement
     /**
      * Set text.
      *
-     * @param $pText string Text
+     * @param $text string Text
      *
      * @return ITextElement
      */
-    public function setText($pText = '')
+    public function setText($text)
     {
-        $this->text = $pText;
+        $this->text = $text;
 
         return $this;
     }
diff --git a/src/PhpSpreadsheet/Settings.php b/src/PhpSpreadsheet/Settings.php
index 62371bdd..e3bac89d 100644
--- a/src/PhpSpreadsheet/Settings.php
+++ b/src/PhpSpreadsheet/Settings.php
@@ -92,7 +92,7 @@ class Settings
      *
      * @return bool Success or failure
      */
-    public static function setLocale($locale = 'en_us')
+    public static function setLocale($locale)
     {
         return Calculation::getInstance()->setLocale($locale);
     }
@@ -208,7 +208,7 @@ class Settings
      *
      * @param int $options Default options for libxml loader
      */
-    public static function setLibXmlLoaderOptions($options = null)
+    public static function setLibXmlLoaderOptions($options)
     {
         if (is_null($options) && defined('LIBXML_DTDLOAD')) {
             $options = LIBXML_DTDLOAD | LIBXML_DTDATTR;
diff --git a/src/PhpSpreadsheet/Shared/CodePage.php b/src/PhpSpreadsheet/Shared/CodePage.php
index 4645e9fd..6e56d231 100644
--- a/src/PhpSpreadsheet/Shared/CodePage.php
+++ b/src/PhpSpreadsheet/Shared/CodePage.php
@@ -36,7 +36,7 @@ class CodePage
      *
      * @return string Code Page Name
      */
-    public static function numberToName($codePage = 1252)
+    public static function numberToName($codePage)
     {
         switch ($codePage) {
             case 367:
diff --git a/src/PhpSpreadsheet/Shared/Date.php b/src/PhpSpreadsheet/Shared/Date.php
index d04e0bdc..cc1638d9 100644
--- a/src/PhpSpreadsheet/Shared/Date.php
+++ b/src/PhpSpreadsheet/Shared/Date.php
@@ -176,7 +176,7 @@ class Date
      *
      * @return \DateTime PHP date/time object
      */
-    public static function excelToDateTimeObject($excelTimestamp = 0, $timeZone = null)
+    public static function excelToDateTimeObject($excelTimestamp, $timeZone = null)
     {
         $timeZone = ($timeZone === null) ? self::getDefaultTimezone() : self::validateTimeZone($timeZone);
         if ($excelTimestamp < 1.0) {
@@ -217,7 +217,7 @@ class Date
      *
      * @return int Unix timetamp for this date/time
      */
-    public static function excelToTimestamp($excelTimestamp = 0, $timeZone = null)
+    public static function excelToTimestamp($excelTimestamp, $timeZone = null)
     {
         return (int) self::excelToDateTimeObject($excelTimestamp, $timeZone)
             ->format('U');
@@ -231,7 +231,7 @@ class Date
      * @return float|bool Excel date/time value
      *                                  or boolean FALSE on failure
      */
-    public static function PHPToExcel($dateValue = 0)
+    public static function PHPToExcel($dateValue)
     {
         if ((is_object($dateValue)) && ($dateValue instanceof \DateTimeInterface)) {
             return self::dateTimeToExcel($dateValue);
@@ -270,7 +270,7 @@ class Date
      *
      * @return float MS Excel serialized date/time value
      */
-    public static function timestampToExcel($dateValue = 0)
+    public static function timestampToExcel($dateValue)
     {
         if (!is_numeric($dateValue)) {
             return false;
@@ -363,7 +363,7 @@ class Date
      *
      * @return bool
      */
-    public static function isDateTimeFormatCode($pFormatCode = '')
+    public static function isDateTimeFormatCode($pFormatCode)
     {
         if (strtolower($pFormatCode) === strtolower(\PhpOffice\PhpSpreadsheet\Style\NumberFormat::FORMAT_GENERAL)) {
             //    "General" contains an epoch letter 'e', so we trap for it explicitly here (case-insensitive check)
@@ -437,7 +437,7 @@ class Date
      *
      * @return float|false Excel date/time serial value
      */
-    public static function stringToExcel($dateValue = '')
+    public static function stringToExcel($dateValue)
     {
         if (strlen($dateValue) < 2) {
             return false;
diff --git a/src/PhpSpreadsheet/Shared/Drawing.php b/src/PhpSpreadsheet/Shared/Drawing.php
index 969d9bf8..436112be 100644
--- a/src/PhpSpreadsheet/Shared/Drawing.php
+++ b/src/PhpSpreadsheet/Shared/Drawing.php
@@ -33,7 +33,7 @@ class Drawing
      *
      * @return int Value in EMU
      */
-    public static function pixelsToEMU($pValue = 0)
+    public static function pixelsToEMU($pValue)
     {
         return round($pValue * 9525);
     }
@@ -45,7 +45,7 @@ class Drawing
      *
      * @return int Value in pixels
      */
-    public static function EMUToPixels($pValue = 0)
+    public static function EMUToPixels($pValue)
     {
         if ($pValue != 0) {
             return round($pValue / 9525);
@@ -118,7 +118,7 @@ class Drawing
      *
      * @return float Value in points
      */
-    public static function pixelsToPoints($pValue = 0)
+    public static function pixelsToPoints($pValue)
     {
         return $pValue * 0.67777777;
     }
@@ -130,7 +130,7 @@ class Drawing
      *
      * @return int Value in pixels
      */
-    public static function pointsToPixels($pValue = 0)
+    public static function pointsToPixels($pValue)
     {
         if ($pValue != 0) {
             return (int) ceil($pValue * 1.333333333);
@@ -146,7 +146,7 @@ class Drawing
      *
      * @return int Angle
      */
-    public static function degreesToAngle($pValue = 0)
+    public static function degreesToAngle($pValue)
     {
         return (int) round($pValue * 60000);
     }
@@ -158,7 +158,7 @@ class Drawing
      *
      * @return int Degrees
      */
-    public static function angleToDegrees($pValue = 0)
+    public static function angleToDegrees($pValue)
     {
         if ($pValue != 0) {
             return round($pValue / 60000);
diff --git a/src/PhpSpreadsheet/Shared/Escher/DgContainer/SpgrContainer/SpContainer.php b/src/PhpSpreadsheet/Shared/Escher/DgContainer/SpgrContainer/SpContainer.php
index a1eac1df..c2b6787a 100644
--- a/src/PhpSpreadsheet/Shared/Escher/DgContainer/SpgrContainer/SpContainer.php
+++ b/src/PhpSpreadsheet/Shared/Escher/DgContainer/SpgrContainer/SpContainer.php
@@ -135,7 +135,7 @@ class SpContainer
      *
      * @param bool $value
      */
-    public function setSpgr($value = false)
+    public function setSpgr($value)
     {
         $this->spgr = $value;
     }
@@ -250,9 +250,9 @@ class SpContainer
     /**
      * Set cell coordinates of upper-left corner of shape.
      *
-     * @param string $value
+     * @param string $value eg: 'A1'
      */
-    public function setStartCoordinates($value = 'A1')
+    public function setStartCoordinates($value)
     {
         $this->startCoordinates = $value;
     }
@@ -272,7 +272,7 @@ class SpContainer
      *
      * @param int $startOffsetX
      */
-    public function setStartOffsetX($startOffsetX = 0)
+    public function setStartOffsetX($startOffsetX)
     {
         $this->startOffsetX = $startOffsetX;
     }
@@ -292,7 +292,7 @@ class SpContainer
      *
      * @param int $startOffsetY
      */
-    public function setStartOffsetY($startOffsetY = 0)
+    public function setStartOffsetY($startOffsetY)
     {
         $this->startOffsetY = $startOffsetY;
     }
@@ -310,9 +310,9 @@ class SpContainer
     /**
      * Set cell coordinates of bottom-right corner of shape.
      *
-     * @param string $value
+     * @param string $value eg: 'A1'
      */
-    public function setEndCoordinates($value = 'A1')
+    public function setEndCoordinates($value)
     {
         $this->endCoordinates = $value;
     }
@@ -332,7 +332,7 @@ class SpContainer
      *
      * @param int $endOffsetX
      */
-    public function setEndOffsetX($endOffsetX = 0)
+    public function setEndOffsetX($endOffsetX)
     {
         $this->endOffsetX = $endOffsetX;
     }
@@ -352,7 +352,7 @@ class SpContainer
      *
      * @param int $endOffsetY
      */
-    public function setEndOffsetY($endOffsetY = 0)
+    public function setEndOffsetY($endOffsetY)
     {
         $this->endOffsetY = $endOffsetY;
     }
diff --git a/src/PhpSpreadsheet/Shared/File.php b/src/PhpSpreadsheet/Shared/File.php
index b6883726..9efd83ff 100644
--- a/src/PhpSpreadsheet/Shared/File.php
+++ b/src/PhpSpreadsheet/Shared/File.php
@@ -42,7 +42,7 @@ class File
      *
      * @param bool $useUploadTempDir Use File Upload Temporary directory (true or false)
      */
-    public static function setUseUploadTempDirectory($useUploadTempDir = false)
+    public static function setUseUploadTempDirectory($useUploadTempDir)
     {
         self::$useUploadTempDirectory = (bool) $useUploadTempDir;
     }
diff --git a/src/PhpSpreadsheet/Shared/Font.php b/src/PhpSpreadsheet/Shared/Font.php
index dbef7701..c305579c 100644
--- a/src/PhpSpreadsheet/Shared/Font.php
+++ b/src/PhpSpreadsheet/Shared/Font.php
@@ -182,11 +182,11 @@ class Font
     /**
      * Set autoSize method.
      *
-     * @param string $pValue
+     * @param string $pValue see self::AUTOSIZE_METHOD_*
      *
      * @return bool Success or failure
      */
-    public static function setAutoSizeMethod($pValue = self::AUTOSIZE_METHOD_APPROX)
+    public static function setAutoSizeMethod($pValue)
     {
         if (!in_array($pValue, self::$autoSizeMethods)) {
             return false;
@@ -217,7 +217,7 @@ class Font
      *
      * @param string $pValue
      */
-    public static function setTrueTypeFontPath($pValue = '')
+    public static function setTrueTypeFontPath($pValue)
     {
         self::$trueTypeFontPath = $pValue;
     }
@@ -382,7 +382,7 @@ class Font
      *
      * @return int Font size (in pixels)
      */
-    public static function fontSizeToPixels($fontSizeInPoints = 11)
+    public static function fontSizeToPixels($fontSizeInPoints)
     {
         return (int) ((4 / 3) * $fontSizeInPoints);
     }
@@ -394,7 +394,7 @@ class Font
      *
      * @return int Size (in pixels)
      */
-    public static function inchSizeToPixels($sizeInInch = 1)
+    public static function inchSizeToPixels($sizeInInch)
     {
         return $sizeInInch * 96;
     }
@@ -406,7 +406,7 @@ class Font
      *
      * @return float Size (in pixels)
      */
-    public static function centimeterSizeToPixels($sizeInCm = 1)
+    public static function centimeterSizeToPixels($sizeInCm)
     {
         return $sizeInCm * 37.795275591;
     }
diff --git a/src/PhpSpreadsheet/Shared/JAMA/CholeskyDecomposition.php b/src/PhpSpreadsheet/Shared/JAMA/CholeskyDecomposition.php
index 79b96566..99d20d8f 100644
--- a/src/PhpSpreadsheet/Shared/JAMA/CholeskyDecomposition.php
+++ b/src/PhpSpreadsheet/Shared/JAMA/CholeskyDecomposition.php
@@ -48,41 +48,35 @@ class CholeskyDecomposition
      * @param mixed Matrix square symmetric positive definite matrix
      * @param null|mixed $A
      */
-    public function __construct($A = null)
+    public function __construct(Matrix $A)
     {
-        if ($A instanceof Matrix) {
-            $this->L = $A->getArray();
-            $this->m = $A->getRowDimension();
+        $this->L = $A->getArray();
+        $this->m = $A->getRowDimension();
 
-            for ($i = 0; $i < $this->m; ++$i) {
-                for ($j = $i; $j < $this->m; ++$j) {
-                    for ($sum = $this->L[$i][$j], $k = $i - 1; $k >= 0; --$k) {
-                        $sum -= $this->L[$i][$k] * $this->L[$j][$k];
-                    }
-                    if ($i == $j) {
-                        if ($sum >= 0) {
-                            $this->L[$i][$i] = sqrt($sum);
-                        } else {
-                            $this->isspd = false;
-                        }
-                    } else {
-                        if ($this->L[$i][$i] != 0) {
-                            $this->L[$j][$i] = $sum / $this->L[$i][$i];
-                        }
-                    }
+        for ($i = 0; $i < $this->m; ++$i) {
+            for ($j = $i; $j < $this->m; ++$j) {
+                for ($sum = $this->L[$i][$j], $k = $i - 1; $k >= 0; --$k) {
+                    $sum -= $this->L[$i][$k] * $this->L[$j][$k];
                 }
-
-                for ($k = $i + 1; $k < $this->m; ++$k) {
-                    $this->L[$i][$k] = 0.0;
+                if ($i == $j) {
+                    if ($sum >= 0) {
+                        $this->L[$i][$i] = sqrt($sum);
+                    } else {
+                        $this->isspd = false;
+                    }
+                } else {
+                    if ($this->L[$i][$i] != 0) {
+                        $this->L[$j][$i] = $sum / $this->L[$i][$i];
+                    }
                 }
             }
-        } else {
-            throw new \PhpOffice\PhpSpreadsheet\Calculation\Exception(JAMAError(ARGUMENT_TYPE_EXCEPTION));
+
+            for ($k = $i + 1; $k < $this->m; ++$k) {
+                $this->L[$i][$k] = 0.0;
+            }
         }
     }
 
-    //    function __construct()
-
     /**
      *    Is the matrix symmetric and positive definite?
      *
@@ -93,8 +87,6 @@ class CholeskyDecomposition
         return $this->isspd;
     }
 
-    //    function isSPD()
-
     /**
      * getL.
      *
@@ -107,8 +99,6 @@ class CholeskyDecomposition
         return new Matrix($this->L);
     }
 
-    //    function getL()
-
     /**
      * Solve A*X = B.
      *
@@ -116,44 +106,39 @@ class CholeskyDecomposition
      *
      * @return Matrix L * L' * X = B
      */
-    public function solve($B = null)
+    public function solve(Matrix $B)
     {
-        if ($B instanceof Matrix) {
-            if ($B->getRowDimension() == $this->m) {
-                if ($this->isspd) {
-                    $X = $B->getArrayCopy();
-                    $nx = $B->getColumnDimension();
+        if ($B->getRowDimension() == $this->m) {
+            if ($this->isspd) {
+                $X = $B->getArrayCopy();
+                $nx = $B->getColumnDimension();
 
-                    for ($k = 0; $k < $this->m; ++$k) {
-                        for ($i = $k + 1; $i < $this->m; ++$i) {
-                            for ($j = 0; $j < $nx; ++$j) {
-                                $X[$i][$j] -= $X[$k][$j] * $this->L[$i][$k];
-                            }
-                        }
+                for ($k = 0; $k < $this->m; ++$k) {
+                    for ($i = $k + 1; $i < $this->m; ++$i) {
                         for ($j = 0; $j < $nx; ++$j) {
-                            $X[$k][$j] /= $this->L[$k][$k];
+                            $X[$i][$j] -= $X[$k][$j] * $this->L[$i][$k];
                         }
                     }
-
-                    for ($k = $this->m - 1; $k >= 0; --$k) {
-                        for ($j = 0; $j < $nx; ++$j) {
-                            $X[$k][$j] /= $this->L[$k][$k];
-                        }
-                        for ($i = 0; $i < $k; ++$i) {
-                            for ($j = 0; $j < $nx; ++$j) {
-                                $X[$i][$j] -= $X[$k][$j] * $this->L[$k][$i];
-                            }
-                        }
+                    for ($j = 0; $j < $nx; ++$j) {
+                        $X[$k][$j] /= $this->L[$k][$k];
                     }
-
-                    return new Matrix($X, $this->m, $nx);
                 }
-                throw new \PhpOffice\PhpSpreadsheet\Calculation\Exception(JAMAError(MatrixSPDException));
-            }
-            throw new \PhpOffice\PhpSpreadsheet\Calculation\Exception(JAMAError(MATRIX_DIMENSION_EXCEPTION));
-        }
-        throw new \PhpOffice\PhpSpreadsheet\Calculation\Exception(JAMAError(ARGUMENT_TYPE_EXCEPTION));
-    }
 
-    //    function solve()
+                for ($k = $this->m - 1; $k >= 0; --$k) {
+                    for ($j = 0; $j < $nx; ++$j) {
+                        $X[$k][$j] /= $this->L[$k][$k];
+                    }
+                    for ($i = 0; $i < $k; ++$i) {
+                        for ($j = 0; $j < $nx; ++$j) {
+                            $X[$i][$j] -= $X[$k][$j] * $this->L[$k][$i];
+                        }
+                    }
+                }
+
+                return new Matrix($X, $this->m, $nx);
+            }
+            throw new \PhpOffice\PhpSpreadsheet\Calculation\Exception(JAMAError(MatrixSPDException));
+        }
+        throw new \PhpOffice\PhpSpreadsheet\Calculation\Exception(JAMAError(MATRIX_DIMENSION_EXCEPTION));
+    }
 }
diff --git a/src/PhpSpreadsheet/Shared/JAMA/utils/Error.php b/src/PhpSpreadsheet/Shared/JAMA/utils/Error.php
index cc6a25e7..8aa78c55 100644
--- a/src/PhpSpreadsheet/Shared/JAMA/utils/Error.php
+++ b/src/PhpSpreadsheet/Shared/JAMA/utils/Error.php
@@ -67,17 +67,13 @@ $error['EN'][ROW_LENGTH_EXCEPTION] = 'All rows must have the same length.';
  *
  * @param int $errorNumber Error number
  */
-function JAMAError($errorNumber = null)
+function JAMAError($errorNumber)
 {
     global $error;
 
-    if (isset($errorNumber)) {
-        if (isset($error[JAMALANG][$errorNumber])) {
-            return $error[JAMALANG][$errorNumber];
-        }
-
-        return $error['EN'][$errorNumber];
+    if (isset($error[JAMALANG][$errorNumber])) {
+        return $error[JAMALANG][$errorNumber];
     }
 
-    return 'Invalid argument to JAMAError()';
+    return $error['EN'][$errorNumber];
 }
diff --git a/src/PhpSpreadsheet/Shared/OLE.php b/src/PhpSpreadsheet/Shared/OLE.php
index 33153c57..a2763f72 100644
--- a/src/PhpSpreadsheet/Shared/OLE.php
+++ b/src/PhpSpreadsheet/Shared/OLE.php
@@ -486,7 +486,7 @@ class OLE
      *
      * @return string The string for the OLE container
      */
-    public static function localDateToOLE($date = null)
+    public static function localDateToOLE($date)
     {
         if (!isset($date)) {
             return "\x00\x00\x00\x00\x00\x00\x00\x00";
diff --git a/src/PhpSpreadsheet/Shared/PasswordHasher.php b/src/PhpSpreadsheet/Shared/PasswordHasher.php
index f47a6573..2a546e0d 100644
--- a/src/PhpSpreadsheet/Shared/PasswordHasher.php
+++ b/src/PhpSpreadsheet/Shared/PasswordHasher.php
@@ -37,7 +37,7 @@ class PasswordHasher
      *
      * @return string Hashed password
      */
-    public static function hashPassword($pPassword = '')
+    public static function hashPassword($pPassword)
     {
         $password = 0x0000;
         $charPos = 1; // char position
diff --git a/src/PhpSpreadsheet/Shared/StringHelper.php b/src/PhpSpreadsheet/Shared/StringHelper.php
index 2273333d..b1d51250 100644
--- a/src/PhpSpreadsheet/Shared/StringHelper.php
+++ b/src/PhpSpreadsheet/Shared/StringHelper.php
@@ -323,7 +323,7 @@ class StringHelper
      *
      * @return string
      */
-    public static function controlCharacterOOXML2PHP($value = '')
+    public static function controlCharacterOOXML2PHP($value)
     {
         return str_replace(array_keys(self::$controlCharacters), array_values(self::$controlCharacters), $value);
     }
@@ -343,7 +343,7 @@ class StringHelper
      *
      * @return string
      */
-    public static function controlCharacterPHP2OOXML($value = '')
+    public static function controlCharacterPHP2OOXML($value)
     {
         return str_replace(array_values(self::$controlCharacters), array_keys(self::$controlCharacters), $value);
     }
@@ -375,7 +375,7 @@ class StringHelper
      *
      * @return bool
      */
-    public static function isUTF8($value = '')
+    public static function isUTF8($value)
     {
         return $value === '' || preg_match('/^./su', $value) === 1;
     }
@@ -499,7 +499,7 @@ class StringHelper
      *
      * @return string
      */
-    public static function substring($pValue = '', $pStart = 0, $pLength = 0)
+    public static function substring($pValue, $pStart, $pLength = 0)
     {
         return mb_substr($pValue, $pStart, $pLength, 'UTF-8');
     }
@@ -511,7 +511,7 @@ class StringHelper
      *
      * @return string
      */
-    public static function strToUpper($pValue = '')
+    public static function strToUpper($pValue)
     {
         return mb_convert_case($pValue, MB_CASE_UPPER, 'UTF-8');
     }
@@ -523,7 +523,7 @@ class StringHelper
      *
      * @return string
      */
-    public static function strToLower($pValue = '')
+    public static function strToLower($pValue)
     {
         return mb_convert_case($pValue, MB_CASE_LOWER, 'UTF-8');
     }
@@ -536,7 +536,7 @@ class StringHelper
      *
      * @return string
      */
-    public static function strToTitle($pValue = '')
+    public static function strToTitle($pValue)
     {
         return mb_convert_case($pValue, MB_CASE_TITLE, 'UTF-8');
     }
@@ -561,7 +561,7 @@ class StringHelper
      *
      * @return string
      */
-    public static function strCaseReverse($pValue = '')
+    public static function strCaseReverse($pValue)
     {
         $characters = self::mbStrSplit($pValue);
         foreach ($characters as &$character) {
@@ -626,7 +626,7 @@ class StringHelper
      *
      * @param string $pValue Character for decimal separator
      */
-    public static function setDecimalSeparator($pValue = '.')
+    public static function setDecimalSeparator($pValue)
     {
         self::$decimalSeparator = $pValue;
     }
@@ -659,7 +659,7 @@ class StringHelper
      *
      * @param string $pValue Character for thousands separator
      */
-    public static function setThousandsSeparator($pValue = ',')
+    public static function setThousandsSeparator($pValue)
     {
         self::$thousandsSeparator = $pValue;
     }
@@ -697,7 +697,7 @@ class StringHelper
      *
      * @param string $pValue Character for currency code
      */
-    public static function setCurrencyCode($pValue = '$')
+    public static function setCurrencyCode($pValue)
     {
         self::$currencyCode = $pValue;
     }
@@ -709,7 +709,7 @@ class StringHelper
      *
      * @return string UTF-8 encoded string
      */
-    public static function SYLKtoUTF8($pValue = '')
+    public static function SYLKtoUTF8($pValue)
     {
         // If there is no escape character in the string there is nothing to do
         if (strpos($pValue, '') === false) {
diff --git a/src/PhpSpreadsheet/Spreadsheet.php b/src/PhpSpreadsheet/Spreadsheet.php
index 1893922f..2724286b 100644
--- a/src/PhpSpreadsheet/Spreadsheet.php
+++ b/src/PhpSpreadsheet/Spreadsheet.php
@@ -148,7 +148,7 @@ class Spreadsheet
      *
      * @param bool $hasMacros true|false
      */
-    public function setHasMacros($hasMacros = false)
+    public function setHasMacros($hasMacros)
     {
         $this->hasMacros = (bool) $hasMacros;
     }
@@ -158,7 +158,7 @@ class Spreadsheet
      *
      * @param string $macroCode string|null
      */
-    public function setMacrosCode($macroCode = null)
+    public function setMacrosCode($macroCode)
     {
         $this->macrosCode = $macroCode;
         $this->setHasMacros(!is_null($macroCode));
@@ -179,7 +179,7 @@ class Spreadsheet
      *
      * @param string|null $certificate
      */
-    public function setMacrosCertificate($certificate = null)
+    public function setMacrosCertificate($certificate)
     {
         $this->macrosCertificate = $certificate;
     }
@@ -220,7 +220,7 @@ class Spreadsheet
      * @param null|mixed $target
      * @param null|mixed $xmlData
      */
-    public function setRibbonXMLData($target = null, $xmlData = null)
+    public function setRibbonXMLData($target, $xmlData)
     {
         if (!is_null($target) && !is_null($xmlData)) {
             $this->ribbonXMLData = ['target' => $target, 'data' => $xmlData];
@@ -234,7 +234,7 @@ class Spreadsheet
      *
      * return string|null|array
      *
-     * @param mixed $what
+     * @param string $what
      *
      * @return string
      */
@@ -263,7 +263,7 @@ class Spreadsheet
      * @param null|mixed $BinObjectsNames
      * @param null|mixed $BinObjectsData
      */
-    public function setRibbonBinObjects($BinObjectsNames = null, $BinObjectsData = null)
+    public function setRibbonBinObjects($BinObjectsNames, $BinObjectsData)
     {
         if (!is_null($BinObjectsNames) && !is_null($BinObjectsData)) {
             $this->ribbonBinObjects = ['names' => $BinObjectsNames, 'data' => $BinObjectsData];
@@ -285,20 +285,20 @@ class Spreadsheet
     /**
      * retrieve Binaries Ribbon Objects.
      *
-     * @param mixed $What
+     * @param mixed $what
      */
-    public function getRibbonBinObjects($What = 'all')
+    public function getRibbonBinObjects($what = 'all')
     {
         $ReturnData = null;
-        $What = strtolower($What);
-        switch ($What) {
+        $what = strtolower($what);
+        switch ($what) {
             case 'all':
                 return $this->ribbonBinObjects;
                 break;
             case 'names':
             case 'data':
-                if (is_array($this->ribbonBinObjects) && isset($this->ribbonBinObjects[$What])) {
-                    $ReturnData = $this->ribbonBinObjects[$What];
+                if (is_array($this->ribbonBinObjects) && isset($this->ribbonBinObjects[$what])) {
+                    $ReturnData = $this->ribbonBinObjects[$what];
                 }
                 break;
             case 'types':
@@ -354,7 +354,7 @@ class Spreadsheet
      *
      * @return Worksheet
      */
-    public function getSheetByCodeName($pName = '')
+    public function getSheetByCodeName($pName)
     {
         $worksheetCount = count($this->workSheetCollection);
         for ($i = 0; $i < $worksheetCount; ++$i) {
@@ -486,16 +486,16 @@ class Spreadsheet
     /**
      * Create sheet and add it to this workbook.
      *
-     * @param int|null $iSheetIndex Index where sheet should go (0,1,..., or null for last)
+     * @param int|null $sheetIndex Index where sheet should go (0,1,..., or null for last)
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function createSheet($iSheetIndex = null)
+    public function createSheet($sheetIndex = null)
     {
         $newSheet = new Worksheet($this);
-        $this->addSheet($newSheet, $iSheetIndex);
+        $this->addSheet($newSheet, $sheetIndex);
 
         return $newSheet;
     }
@@ -564,7 +564,7 @@ class Spreadsheet
      *
      * @throws Exception
      */
-    public function removeSheetByIndex($pIndex = 0)
+    public function removeSheetByIndex($pIndex)
     {
         $numSheets = count($this->workSheetCollection);
         if ($pIndex > $numSheets - 1) {
@@ -590,7 +590,7 @@ class Spreadsheet
      *
      * @return Worksheet
      */
-    public function getSheet($pIndex = 0)
+    public function getSheet($pIndex)
     {
         if (!isset($this->workSheetCollection[$pIndex])) {
             $numSheets = $this->getSheetCount();
@@ -619,7 +619,7 @@ class Spreadsheet
      *
      * @return Worksheet
      */
-    public function getSheetByName($pName = '')
+    public function getSheetByName($pName)
     {
         $worksheetCount = count($this->workSheetCollection);
         for ($i = 0; $i < $worksheetCount; ++$i) {
@@ -708,7 +708,7 @@ class Spreadsheet
      *
      * @return Worksheet
      */
-    public function setActiveSheetIndex($pIndex = 0)
+    public function setActiveSheetIndex($pIndex)
     {
         $numSheets = count($this->workSheetCollection);
 
@@ -731,7 +731,7 @@ class Spreadsheet
      *
      * @return Worksheet
      */
-    public function setActiveSheetIndexByName($pValue = '')
+    public function setActiveSheetIndexByName($pValue)
     {
         if (($worksheet = $this->getSheetByName($pValue)) instanceof Worksheet) {
             $this->setActiveSheetIndex($this->getIndex($worksheet));
@@ -931,7 +931,7 @@ class Spreadsheet
      *
      * @return Style
      */
-    public function getCellXfByIndex($pIndex = 0)
+    public function getCellXfByIndex($pIndex)
     {
         return $this->cellXfCollection[$pIndex];
     }
@@ -943,7 +943,7 @@ class Spreadsheet
      *
      * @return Style|false
      */
-    public function getCellXfByHashCode($pValue = '')
+    public function getCellXfByHashCode($pValue)
     {
         foreach ($this->cellXfCollection as $cellXf) {
             if ($cellXf->getHashCode() == $pValue) {
@@ -961,7 +961,7 @@ class Spreadsheet
      *
      * @return bool
      */
-    public function cellXfExists($pCellStyle = null)
+    public function cellXfExists($pCellStyle)
     {
         return in_array($pCellStyle, $this->cellXfCollection, true);
     }
@@ -999,7 +999,7 @@ class Spreadsheet
      *
      * @throws Exception
      */
-    public function removeCellXfByIndex($pIndex = 0)
+    public function removeCellXfByIndex($pIndex)
     {
         if ($pIndex > count($this->cellXfCollection) - 1) {
             throw new Exception('CellXf index is out of bounds.');
@@ -1051,7 +1051,7 @@ class Spreadsheet
      *
      * @return Style
      */
-    public function getCellStyleXfByIndex($pIndex = 0)
+    public function getCellStyleXfByIndex($pIndex)
     {
         return $this->cellStyleXfCollection[$pIndex];
     }
@@ -1063,7 +1063,7 @@ class Spreadsheet
      *
      * @return Style|false
      */
-    public function getCellStyleXfByHashCode($pValue = '')
+    public function getCellStyleXfByHashCode($pValue)
     {
         foreach ($this->cellStyleXfCollection as $cellStyleXf) {
             if ($cellStyleXf->getHashCode() == $pValue) {
@@ -1092,7 +1092,7 @@ class Spreadsheet
      *
      * @throws Exception
      */
-    public function removeCellStyleXfByIndex($pIndex = 0)
+    public function removeCellStyleXfByIndex($pIndex)
     {
         if ($pIndex > count($this->cellStyleXfCollection) - 1) {
             throw new Exception('CellStyleXf index is out of bounds.');
diff --git a/src/PhpSpreadsheet/Style.php b/src/PhpSpreadsheet/Style.php
index b8c0675f..65902077 100644
--- a/src/PhpSpreadsheet/Style.php
+++ b/src/PhpSpreadsheet/Style.php
@@ -208,263 +208,259 @@ class Style extends Style\Supervisor implements IComparable
      *
      * @return Style
      */
-    public function applyFromArray($pStyles = null, $pAdvanced = true)
+    public function applyFromArray(array $pStyles, $pAdvanced = true)
     {
-        if (is_array($pStyles)) {
-            if ($this->isSupervisor) {
-                $pRange = $this->getSelectedCells();
+        if ($this->isSupervisor) {
+            $pRange = $this->getSelectedCells();
 
-                // Uppercase coordinate
-                $pRange = strtoupper($pRange);
+            // Uppercase coordinate
+            $pRange = strtoupper($pRange);
 
-                // Is it a cell range or a single cell?
-                if (strpos($pRange, ':') === false) {
-                    $rangeA = $pRange;
-                    $rangeB = $pRange;
-                } else {
-                    list($rangeA, $rangeB) = explode(':', $pRange);
-                }
-
-                // Calculate range outer borders
-                $rangeStart = Cell::coordinateFromString($rangeA);
-                $rangeEnd = Cell::coordinateFromString($rangeB);
-
-                // Translate column into index
-                $rangeStart[0] = Cell::columnIndexFromString($rangeStart[0]) - 1;
-                $rangeEnd[0] = Cell::columnIndexFromString($rangeEnd[0]) - 1;
-
-                // Make sure we can loop upwards on rows and columns
-                if ($rangeStart[0] > $rangeEnd[0] && $rangeStart[1] > $rangeEnd[1]) {
-                    $tmp = $rangeStart;
-                    $rangeStart = $rangeEnd;
-                    $rangeEnd = $tmp;
-                }
-
-                // ADVANCED MODE:
-                if ($pAdvanced && isset($pStyles['borders'])) {
-                    // 'allborders' is a shorthand property for 'outline' and 'inside' and
-                    //        it applies to components that have not been set explicitly
-                    if (isset($pStyles['borders']['allborders'])) {
-                        foreach (['outline', 'inside'] as $component) {
-                            if (!isset($pStyles['borders'][$component])) {
-                                $pStyles['borders'][$component] = $pStyles['borders']['allborders'];
-                            }
-                        }
-                        unset($pStyles['borders']['allborders']); // not needed any more
-                    }
-                    // 'outline' is a shorthand property for 'top', 'right', 'bottom', 'left'
-                    //        it applies to components that have not been set explicitly
-                    if (isset($pStyles['borders']['outline'])) {
-                        foreach (['top', 'right', 'bottom', 'left'] as $component) {
-                            if (!isset($pStyles['borders'][$component])) {
-                                $pStyles['borders'][$component] = $pStyles['borders']['outline'];
-                            }
-                        }
-                        unset($pStyles['borders']['outline']); // not needed any more
-                    }
-                    // 'inside' is a shorthand property for 'vertical' and 'horizontal'
-                    //        it applies to components that have not been set explicitly
-                    if (isset($pStyles['borders']['inside'])) {
-                        foreach (['vertical', 'horizontal'] as $component) {
-                            if (!isset($pStyles['borders'][$component])) {
-                                $pStyles['borders'][$component] = $pStyles['borders']['inside'];
-                            }
-                        }
-                        unset($pStyles['borders']['inside']); // not needed any more
-                    }
-                    // width and height characteristics of selection, 1, 2, or 3 (for 3 or more)
-                    $xMax = min($rangeEnd[0] - $rangeStart[0] + 1, 3);
-                    $yMax = min($rangeEnd[1] - $rangeStart[1] + 1, 3);
-
-                    // loop through up to 3 x 3 = 9 regions
-                    for ($x = 1; $x <= $xMax; ++$x) {
-                        // start column index for region
-                        $colStart = ($x == 3) ?
-                            Cell::stringFromColumnIndex($rangeEnd[0])
-                                : Cell::stringFromColumnIndex($rangeStart[0] + $x - 1);
-                        // end column index for region
-                        $colEnd = ($x == 1) ?
-                            Cell::stringFromColumnIndex($rangeStart[0])
-                                : Cell::stringFromColumnIndex($rangeEnd[0] - $xMax + $x);
-
-                        for ($y = 1; $y <= $yMax; ++$y) {
-                            // which edges are touching the region
-                            $edges = [];
-                            if ($x == 1) {
-                                // are we at left edge
-                                $edges[] = 'left';
-                            }
-                            if ($x == $xMax) {
-                                // are we at right edge
-                                $edges[] = 'right';
-                            }
-                            if ($y == 1) {
-                                // are we at top edge?
-                                $edges[] = 'top';
-                            }
-                            if ($y == $yMax) {
-                                // are we at bottom edge?
-                                $edges[] = 'bottom';
-                            }
-
-                            // start row index for region
-                            $rowStart = ($y == 3) ?
-                                $rangeEnd[1] : $rangeStart[1] + $y - 1;
-
-                            // end row index for region
-                            $rowEnd = ($y == 1) ?
-                                $rangeStart[1] : $rangeEnd[1] - $yMax + $y;
-
-                            // build range for region
-                            $range = $colStart . $rowStart . ':' . $colEnd . $rowEnd;
-
-                            // retrieve relevant style array for region
-                            $regionStyles = $pStyles;
-                            unset($regionStyles['borders']['inside']);
-
-                            // what are the inner edges of the region when looking at the selection
-                            $innerEdges = array_diff(['top', 'right', 'bottom', 'left'], $edges);
-
-                            // inner edges that are not touching the region should take the 'inside' border properties if they have been set
-                            foreach ($innerEdges as $innerEdge) {
-                                switch ($innerEdge) {
-                                    case 'top':
-                                    case 'bottom':
-                                        // should pick up 'horizontal' border property if set
-                                        if (isset($pStyles['borders']['horizontal'])) {
-                                            $regionStyles['borders'][$innerEdge] = $pStyles['borders']['horizontal'];
-                                        } else {
-                                            unset($regionStyles['borders'][$innerEdge]);
-                                        }
-                                        break;
-                                    case 'left':
-                                    case 'right':
-                                        // should pick up 'vertical' border property if set
-                                        if (isset($pStyles['borders']['vertical'])) {
-                                            $regionStyles['borders'][$innerEdge] = $pStyles['borders']['vertical'];
-                                        } else {
-                                            unset($regionStyles['borders'][$innerEdge]);
-                                        }
-                                        break;
-                                }
-                            }
-
-                            // apply region style to region by calling applyFromArray() in simple mode
-                            $this->getActiveSheet()->getStyle($range)->applyFromArray($regionStyles, false);
-                        }
-                    }
-
-                    return $this;
-                }
-
-                // SIMPLE MODE:
-                // Selection type, inspect
-                if (preg_match('/^[A-Z]+1:[A-Z]+1048576$/', $pRange)) {
-                    $selectionType = 'COLUMN';
-                } elseif (preg_match('/^A[0-9]+:XFD[0-9]+$/', $pRange)) {
-                    $selectionType = 'ROW';
-                } else {
-                    $selectionType = 'CELL';
-                }
-
-                // First loop through columns, rows, or cells to find out which styles are affected by this operation
-                switch ($selectionType) {
-                    case 'COLUMN':
-                        $oldXfIndexes = [];
-                        for ($col = $rangeStart[0]; $col <= $rangeEnd[0]; ++$col) {
-                            $oldXfIndexes[$this->getActiveSheet()->getColumnDimensionByColumn($col)->getXfIndex()] = true;
-                        }
-                        break;
-                    case 'ROW':
-                        $oldXfIndexes = [];
-                        for ($row = $rangeStart[1]; $row <= $rangeEnd[1]; ++$row) {
-                            if ($this->getActiveSheet()->getRowDimension($row)->getXfIndex() == null) {
-                                $oldXfIndexes[0] = true; // row without explicit style should be formatted based on default style
-                            } else {
-                                $oldXfIndexes[$this->getActiveSheet()->getRowDimension($row)->getXfIndex()] = true;
-                            }
-                        }
-                        break;
-                    case 'CELL':
-                        $oldXfIndexes = [];
-                        for ($col = $rangeStart[0]; $col <= $rangeEnd[0]; ++$col) {
-                            for ($row = $rangeStart[1]; $row <= $rangeEnd[1]; ++$row) {
-                                $oldXfIndexes[$this->getActiveSheet()->getCellByColumnAndRow($col, $row)->getXfIndex()] = true;
-                            }
-                        }
-                        break;
-                }
-
-                // clone each of the affected styles, apply the style array, and add the new styles to the workbook
-                $workbook = $this->getActiveSheet()->getParent();
-                foreach ($oldXfIndexes as $oldXfIndex => $dummy) {
-                    $style = $workbook->getCellXfByIndex($oldXfIndex);
-                    $newStyle = clone $style;
-                    $newStyle->applyFromArray($pStyles);
-
-                    if ($existingStyle = $workbook->getCellXfByHashCode($newStyle->getHashCode())) {
-                        // there is already such cell Xf in our collection
-                        $newXfIndexes[$oldXfIndex] = $existingStyle->getIndex();
-                    } else {
-                        // we don't have such a cell Xf, need to add
-                        $workbook->addCellXf($newStyle);
-                        $newXfIndexes[$oldXfIndex] = $newStyle->getIndex();
-                    }
-                }
-
-                // Loop through columns, rows, or cells again and update the XF index
-                switch ($selectionType) {
-                    case 'COLUMN':
-                        for ($col = $rangeStart[0]; $col <= $rangeEnd[0]; ++$col) {
-                            $columnDimension = $this->getActiveSheet()->getColumnDimensionByColumn($col);
-                            $oldXfIndex = $columnDimension->getXfIndex();
-                            $columnDimension->setXfIndex($newXfIndexes[$oldXfIndex]);
-                        }
-                        break;
-                    case 'ROW':
-                        for ($row = $rangeStart[1]; $row <= $rangeEnd[1]; ++$row) {
-                            $rowDimension = $this->getActiveSheet()->getRowDimension($row);
-                            $oldXfIndex = $rowDimension->getXfIndex() === null ?
-                                0 : $rowDimension->getXfIndex(); // row without explicit style should be formatted based on default style
-                            $rowDimension->setXfIndex($newXfIndexes[$oldXfIndex]);
-                        }
-                        break;
-                    case 'CELL':
-                        for ($col = $rangeStart[0]; $col <= $rangeEnd[0]; ++$col) {
-                            for ($row = $rangeStart[1]; $row <= $rangeEnd[1]; ++$row) {
-                                $cell = $this->getActiveSheet()->getCellByColumnAndRow($col, $row);
-                                $oldXfIndex = $cell->getXfIndex();
-                                $cell->setXfIndex($newXfIndexes[$oldXfIndex]);
-                            }
-                        }
-                        break;
-                }
+            // Is it a cell range or a single cell?
+            if (strpos($pRange, ':') === false) {
+                $rangeA = $pRange;
+                $rangeB = $pRange;
             } else {
-                // not a supervisor, just apply the style array directly on style object
-                if (isset($pStyles['fill'])) {
-                    $this->getFill()->applyFromArray($pStyles['fill']);
+                list($rangeA, $rangeB) = explode(':', $pRange);
+            }
+
+            // Calculate range outer borders
+            $rangeStart = Cell::coordinateFromString($rangeA);
+            $rangeEnd = Cell::coordinateFromString($rangeB);
+
+            // Translate column into index
+            $rangeStart[0] = Cell::columnIndexFromString($rangeStart[0]) - 1;
+            $rangeEnd[0] = Cell::columnIndexFromString($rangeEnd[0]) - 1;
+
+            // Make sure we can loop upwards on rows and columns
+            if ($rangeStart[0] > $rangeEnd[0] && $rangeStart[1] > $rangeEnd[1]) {
+                $tmp = $rangeStart;
+                $rangeStart = $rangeEnd;
+                $rangeEnd = $tmp;
+            }
+
+            // ADVANCED MODE:
+            if ($pAdvanced && isset($pStyles['borders'])) {
+                // 'allborders' is a shorthand property for 'outline' and 'inside' and
+                //        it applies to components that have not been set explicitly
+                if (isset($pStyles['borders']['allborders'])) {
+                    foreach (['outline', 'inside'] as $component) {
+                        if (!isset($pStyles['borders'][$component])) {
+                            $pStyles['borders'][$component] = $pStyles['borders']['allborders'];
+                        }
+                    }
+                    unset($pStyles['borders']['allborders']); // not needed any more
                 }
-                if (isset($pStyles['font'])) {
-                    $this->getFont()->applyFromArray($pStyles['font']);
+                // 'outline' is a shorthand property for 'top', 'right', 'bottom', 'left'
+                //        it applies to components that have not been set explicitly
+                if (isset($pStyles['borders']['outline'])) {
+                    foreach (['top', 'right', 'bottom', 'left'] as $component) {
+                        if (!isset($pStyles['borders'][$component])) {
+                            $pStyles['borders'][$component] = $pStyles['borders']['outline'];
+                        }
+                    }
+                    unset($pStyles['borders']['outline']); // not needed any more
                 }
-                if (isset($pStyles['borders'])) {
-                    $this->getBorders()->applyFromArray($pStyles['borders']);
+                // 'inside' is a shorthand property for 'vertical' and 'horizontal'
+                //        it applies to components that have not been set explicitly
+                if (isset($pStyles['borders']['inside'])) {
+                    foreach (['vertical', 'horizontal'] as $component) {
+                        if (!isset($pStyles['borders'][$component])) {
+                            $pStyles['borders'][$component] = $pStyles['borders']['inside'];
+                        }
+                    }
+                    unset($pStyles['borders']['inside']); // not needed any more
                 }
-                if (isset($pStyles['alignment'])) {
-                    $this->getAlignment()->applyFromArray($pStyles['alignment']);
+                // width and height characteristics of selection, 1, 2, or 3 (for 3 or more)
+                $xMax = min($rangeEnd[0] - $rangeStart[0] + 1, 3);
+                $yMax = min($rangeEnd[1] - $rangeStart[1] + 1, 3);
+
+                // loop through up to 3 x 3 = 9 regions
+                for ($x = 1; $x <= $xMax; ++$x) {
+                    // start column index for region
+                    $colStart = ($x == 3) ?
+                        Cell::stringFromColumnIndex($rangeEnd[0])
+                            : Cell::stringFromColumnIndex($rangeStart[0] + $x - 1);
+                    // end column index for region
+                    $colEnd = ($x == 1) ?
+                        Cell::stringFromColumnIndex($rangeStart[0])
+                            : Cell::stringFromColumnIndex($rangeEnd[0] - $xMax + $x);
+
+                    for ($y = 1; $y <= $yMax; ++$y) {
+                        // which edges are touching the region
+                        $edges = [];
+                        if ($x == 1) {
+                            // are we at left edge
+                            $edges[] = 'left';
+                        }
+                        if ($x == $xMax) {
+                            // are we at right edge
+                            $edges[] = 'right';
+                        }
+                        if ($y == 1) {
+                            // are we at top edge?
+                            $edges[] = 'top';
+                        }
+                        if ($y == $yMax) {
+                            // are we at bottom edge?
+                            $edges[] = 'bottom';
+                        }
+
+                        // start row index for region
+                        $rowStart = ($y == 3) ?
+                            $rangeEnd[1] : $rangeStart[1] + $y - 1;
+
+                        // end row index for region
+                        $rowEnd = ($y == 1) ?
+                            $rangeStart[1] : $rangeEnd[1] - $yMax + $y;
+
+                        // build range for region
+                        $range = $colStart . $rowStart . ':' . $colEnd . $rowEnd;
+
+                        // retrieve relevant style array for region
+                        $regionStyles = $pStyles;
+                        unset($regionStyles['borders']['inside']);
+
+                        // what are the inner edges of the region when looking at the selection
+                        $innerEdges = array_diff(['top', 'right', 'bottom', 'left'], $edges);
+
+                        // inner edges that are not touching the region should take the 'inside' border properties if they have been set
+                        foreach ($innerEdges as $innerEdge) {
+                            switch ($innerEdge) {
+                                case 'top':
+                                case 'bottom':
+                                    // should pick up 'horizontal' border property if set
+                                    if (isset($pStyles['borders']['horizontal'])) {
+                                        $regionStyles['borders'][$innerEdge] = $pStyles['borders']['horizontal'];
+                                    } else {
+                                        unset($regionStyles['borders'][$innerEdge]);
+                                    }
+                                    break;
+                                case 'left':
+                                case 'right':
+                                    // should pick up 'vertical' border property if set
+                                    if (isset($pStyles['borders']['vertical'])) {
+                                        $regionStyles['borders'][$innerEdge] = $pStyles['borders']['vertical'];
+                                    } else {
+                                        unset($regionStyles['borders'][$innerEdge]);
+                                    }
+                                    break;
+                            }
+                        }
+
+                        // apply region style to region by calling applyFromArray() in simple mode
+                        $this->getActiveSheet()->getStyle($range)->applyFromArray($regionStyles, false);
+                    }
                 }
-                if (isset($pStyles['numberformat'])) {
-                    $this->getNumberFormat()->applyFromArray($pStyles['numberformat']);
-                }
-                if (isset($pStyles['protection'])) {
-                    $this->getProtection()->applyFromArray($pStyles['protection']);
-                }
-                if (isset($pStyles['quotePrefix'])) {
-                    $this->quotePrefix = $pStyles['quotePrefix'];
+
+                return $this;
+            }
+
+            // SIMPLE MODE:
+            // Selection type, inspect
+            if (preg_match('/^[A-Z]+1:[A-Z]+1048576$/', $pRange)) {
+                $selectionType = 'COLUMN';
+            } elseif (preg_match('/^A[0-9]+:XFD[0-9]+$/', $pRange)) {
+                $selectionType = 'ROW';
+            } else {
+                $selectionType = 'CELL';
+            }
+
+            // First loop through columns, rows, or cells to find out which styles are affected by this operation
+            switch ($selectionType) {
+                case 'COLUMN':
+                    $oldXfIndexes = [];
+                    for ($col = $rangeStart[0]; $col <= $rangeEnd[0]; ++$col) {
+                        $oldXfIndexes[$this->getActiveSheet()->getColumnDimensionByColumn($col)->getXfIndex()] = true;
+                    }
+                    break;
+                case 'ROW':
+                    $oldXfIndexes = [];
+                    for ($row = $rangeStart[1]; $row <= $rangeEnd[1]; ++$row) {
+                        if ($this->getActiveSheet()->getRowDimension($row)->getXfIndex() == null) {
+                            $oldXfIndexes[0] = true; // row without explicit style should be formatted based on default style
+                        } else {
+                            $oldXfIndexes[$this->getActiveSheet()->getRowDimension($row)->getXfIndex()] = true;
+                        }
+                    }
+                    break;
+                case 'CELL':
+                    $oldXfIndexes = [];
+                    for ($col = $rangeStart[0]; $col <= $rangeEnd[0]; ++$col) {
+                        for ($row = $rangeStart[1]; $row <= $rangeEnd[1]; ++$row) {
+                            $oldXfIndexes[$this->getActiveSheet()->getCellByColumnAndRow($col, $row)->getXfIndex()] = true;
+                        }
+                    }
+                    break;
+            }
+
+            // clone each of the affected styles, apply the style array, and add the new styles to the workbook
+            $workbook = $this->getActiveSheet()->getParent();
+            foreach ($oldXfIndexes as $oldXfIndex => $dummy) {
+                $style = $workbook->getCellXfByIndex($oldXfIndex);
+                $newStyle = clone $style;
+                $newStyle->applyFromArray($pStyles);
+
+                if ($existingStyle = $workbook->getCellXfByHashCode($newStyle->getHashCode())) {
+                    // there is already such cell Xf in our collection
+                    $newXfIndexes[$oldXfIndex] = $existingStyle->getIndex();
+                } else {
+                    // we don't have such a cell Xf, need to add
+                    $workbook->addCellXf($newStyle);
+                    $newXfIndexes[$oldXfIndex] = $newStyle->getIndex();
                 }
             }
+
+            // Loop through columns, rows, or cells again and update the XF index
+            switch ($selectionType) {
+                case 'COLUMN':
+                    for ($col = $rangeStart[0]; $col <= $rangeEnd[0]; ++$col) {
+                        $columnDimension = $this->getActiveSheet()->getColumnDimensionByColumn($col);
+                        $oldXfIndex = $columnDimension->getXfIndex();
+                        $columnDimension->setXfIndex($newXfIndexes[$oldXfIndex]);
+                    }
+                    break;
+                case 'ROW':
+                    for ($row = $rangeStart[1]; $row <= $rangeEnd[1]; ++$row) {
+                        $rowDimension = $this->getActiveSheet()->getRowDimension($row);
+                        $oldXfIndex = $rowDimension->getXfIndex() === null ?
+                            0 : $rowDimension->getXfIndex(); // row without explicit style should be formatted based on default style
+                        $rowDimension->setXfIndex($newXfIndexes[$oldXfIndex]);
+                    }
+                    break;
+                case 'CELL':
+                    for ($col = $rangeStart[0]; $col <= $rangeEnd[0]; ++$col) {
+                        for ($row = $rangeStart[1]; $row <= $rangeEnd[1]; ++$row) {
+                            $cell = $this->getActiveSheet()->getCellByColumnAndRow($col, $row);
+                            $oldXfIndex = $cell->getXfIndex();
+                            $cell->setXfIndex($newXfIndexes[$oldXfIndex]);
+                        }
+                    }
+                    break;
+            }
         } else {
-            throw new Exception('Invalid style array passed.');
+            // not a supervisor, just apply the style array directly on style object
+            if (isset($pStyles['fill'])) {
+                $this->getFill()->applyFromArray($pStyles['fill']);
+            }
+            if (isset($pStyles['font'])) {
+                $this->getFont()->applyFromArray($pStyles['font']);
+            }
+            if (isset($pStyles['borders'])) {
+                $this->getBorders()->applyFromArray($pStyles['borders']);
+            }
+            if (isset($pStyles['alignment'])) {
+                $this->getAlignment()->applyFromArray($pStyles['alignment']);
+            }
+            if (isset($pStyles['numberformat'])) {
+                $this->getNumberFormat()->applyFromArray($pStyles['numberformat']);
+            }
+            if (isset($pStyles['protection'])) {
+                $this->getProtection()->applyFromArray($pStyles['protection']);
+            }
+            if (isset($pStyles['quotePrefix'])) {
+                $this->quotePrefix = $pStyles['quotePrefix'];
+            }
         }
 
         return $this;
@@ -547,15 +543,13 @@ class Style extends Style\Supervisor implements IComparable
     /**
      * Set Conditional Styles. Only used on supervisor.
      *
-     * @param Style\Conditional[] $pValue Array of condtional styles
+     * @param Style\Conditional[] $pValue Array of conditional styles
      *
      * @return Style
      */
-    public function setConditionalStyles($pValue = null)
+    public function setConditionalStyles(array $pValue)
     {
-        if (is_array($pValue)) {
-            $this->getActiveSheet()->setConditionalStyles($this->getSelectedCells(), $pValue);
-        }
+        $this->getActiveSheet()->setConditionalStyles($this->getSelectedCells(), $pValue);
 
         return $this;
     }
diff --git a/src/PhpSpreadsheet/Style/Alignment.php b/src/PhpSpreadsheet/Style/Alignment.php
index 68ded6c4..6ee25160 100644
--- a/src/PhpSpreadsheet/Style/Alignment.php
+++ b/src/PhpSpreadsheet/Style/Alignment.php
@@ -162,37 +162,33 @@ class Alignment extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompara
      *
      * @return Alignment
      */
-    public function applyFromArray($pStyles = null)
+    public function applyFromArray(array $pStyles)
     {
-        if (is_array($pStyles)) {
-            if ($this->isSupervisor) {
-                $this->getActiveSheet()->getStyle($this->getSelectedCells())
-                    ->applyFromArray($this->getStyleArray($pStyles));
-            } else {
-                if (isset($pStyles['horizontal'])) {
-                    $this->setHorizontal($pStyles['horizontal']);
-                }
-                if (isset($pStyles['vertical'])) {
-                    $this->setVertical($pStyles['vertical']);
-                }
-                if (isset($pStyles['rotation'])) {
-                    $this->setTextRotation($pStyles['rotation']);
-                }
-                if (isset($pStyles['wrap'])) {
-                    $this->setWrapText($pStyles['wrap']);
-                }
-                if (isset($pStyles['shrinkToFit'])) {
-                    $this->setShrinkToFit($pStyles['shrinkToFit']);
-                }
-                if (isset($pStyles['indent'])) {
-                    $this->setIndent($pStyles['indent']);
-                }
-                if (isset($pStyles['readorder'])) {
-                    $this->setReadorder($pStyles['readorder']);
-                }
-            }
+        if ($this->isSupervisor) {
+            $this->getActiveSheet()->getStyle($this->getSelectedCells())
+                ->applyFromArray($this->getStyleArray($pStyles));
         } else {
-            throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid style array passed.');
+            if (isset($pStyles['horizontal'])) {
+                $this->setHorizontal($pStyles['horizontal']);
+            }
+            if (isset($pStyles['vertical'])) {
+                $this->setVertical($pStyles['vertical']);
+            }
+            if (isset($pStyles['rotation'])) {
+                $this->setTextRotation($pStyles['rotation']);
+            }
+            if (isset($pStyles['wrap'])) {
+                $this->setWrapText($pStyles['wrap']);
+            }
+            if (isset($pStyles['shrinkToFit'])) {
+                $this->setShrinkToFit($pStyles['shrinkToFit']);
+            }
+            if (isset($pStyles['indent'])) {
+                $this->setIndent($pStyles['indent']);
+            }
+            if (isset($pStyles['readorder'])) {
+                $this->setReadorder($pStyles['readorder']);
+            }
         }
 
         return $this;
@@ -215,11 +211,11 @@ class Alignment extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompara
     /**
      * Set Horizontal.
      *
-     * @param string $pValue
+     * @param string $pValue see self::HORIZONTAL_*
      *
      * @return Alignment
      */
-    public function setHorizontal($pValue = self::HORIZONTAL_GENERAL)
+    public function setHorizontal($pValue)
     {
         if ($pValue == '') {
             $pValue = self::HORIZONTAL_GENERAL;
@@ -252,11 +248,11 @@ class Alignment extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompara
     /**
      * Set Vertical.
      *
-     * @param string $pValue
+     * @param string $pValue see self::VERTICAL_*
      *
      * @return Alignment
      */
-    public function setVertical($pValue = self::VERTICAL_BOTTOM)
+    public function setVertical($pValue)
     {
         if ($pValue == '') {
             $pValue = self::VERTICAL_BOTTOM;
@@ -295,7 +291,7 @@ class Alignment extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompara
      *
      * @return Alignment
      */
-    public function setTextRotation($pValue = 0)
+    public function setTextRotation($pValue)
     {
         // Excel2007 value 255 => PhpSpreadsheet value -165
         if ($pValue == 255) {
@@ -338,7 +334,7 @@ class Alignment extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompara
      *
      * @return Alignment
      */
-    public function setWrapText($pValue = false)
+    public function setWrapText($pValue)
     {
         if ($pValue == '') {
             $pValue = false;
@@ -374,7 +370,7 @@ class Alignment extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompara
      *
      * @return Alignment
      */
-    public function setShrinkToFit($pValue = false)
+    public function setShrinkToFit($pValue)
     {
         if ($pValue == '') {
             $pValue = false;
@@ -410,7 +406,7 @@ class Alignment extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompara
      *
      * @return Alignment
      */
-    public function setIndent($pValue = 0)
+    public function setIndent($pValue)
     {
         if ($pValue > 0) {
             if ($this->getHorizontal() != self::HORIZONTAL_GENERAL &&
@@ -450,7 +446,7 @@ class Alignment extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompara
      *
      * @return Alignment
      */
-    public function setReadorder($pValue = 0)
+    public function setReadorder($pValue)
     {
         if ($pValue < 0 || $pValue > 2) {
             $pValue = 0;
diff --git a/src/PhpSpreadsheet/Style/Border.php b/src/PhpSpreadsheet/Style/Border.php
index 8eed8981..48497aa5 100644
--- a/src/PhpSpreadsheet/Style/Border.php
+++ b/src/PhpSpreadsheet/Style/Border.php
@@ -181,21 +181,17 @@ class Border extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Border
      */
-    public function applyFromArray($pStyles = null)
+    public function applyFromArray(array $pStyles)
     {
-        if (is_array($pStyles)) {
-            if ($this->isSupervisor) {
-                $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
-            } else {
-                if (isset($pStyles['style'])) {
-                    $this->setBorderStyle($pStyles['style']);
-                }
-                if (isset($pStyles['color'])) {
-                    $this->getColor()->applyFromArray($pStyles['color']);
-                }
-            }
+        if ($this->isSupervisor) {
+            $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
         } else {
-            throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid style array passed.');
+            if (isset($pStyles['style'])) {
+                $this->setBorderStyle($pStyles['style']);
+            }
+            if (isset($pStyles['color'])) {
+                $this->getColor()->applyFromArray($pStyles['color']);
+            }
         }
 
         return $this;
@@ -224,7 +220,7 @@ class Border extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Border
      */
-    public function setBorderStyle($pValue = self::BORDER_NONE)
+    public function setBorderStyle($pValue)
     {
         if (empty($pValue)) {
             $pValue = self::BORDER_NONE;
diff --git a/src/PhpSpreadsheet/Style/Borders.php b/src/PhpSpreadsheet/Style/Borders.php
index 674da8fb..06268d8b 100644
--- a/src/PhpSpreadsheet/Style/Borders.php
+++ b/src/PhpSpreadsheet/Style/Borders.php
@@ -218,39 +218,35 @@ class Borders extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparabl
      *
      * @return Borders
      */
-    public function applyFromArray($pStyles = null)
+    public function applyFromArray(array $pStyles)
     {
-        if (is_array($pStyles)) {
-            if ($this->isSupervisor) {
-                $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
-            } else {
-                if (isset($pStyles['left'])) {
-                    $this->getLeft()->applyFromArray($pStyles['left']);
-                }
-                if (isset($pStyles['right'])) {
-                    $this->getRight()->applyFromArray($pStyles['right']);
-                }
-                if (isset($pStyles['top'])) {
-                    $this->getTop()->applyFromArray($pStyles['top']);
-                }
-                if (isset($pStyles['bottom'])) {
-                    $this->getBottom()->applyFromArray($pStyles['bottom']);
-                }
-                if (isset($pStyles['diagonal'])) {
-                    $this->getDiagonal()->applyFromArray($pStyles['diagonal']);
-                }
-                if (isset($pStyles['diagonaldirection'])) {
-                    $this->setDiagonalDirection($pStyles['diagonaldirection']);
-                }
-                if (isset($pStyles['allborders'])) {
-                    $this->getLeft()->applyFromArray($pStyles['allborders']);
-                    $this->getRight()->applyFromArray($pStyles['allborders']);
-                    $this->getTop()->applyFromArray($pStyles['allborders']);
-                    $this->getBottom()->applyFromArray($pStyles['allborders']);
-                }
-            }
+        if ($this->isSupervisor) {
+            $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
         } else {
-            throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid style array passed.');
+            if (isset($pStyles['left'])) {
+                $this->getLeft()->applyFromArray($pStyles['left']);
+            }
+            if (isset($pStyles['right'])) {
+                $this->getRight()->applyFromArray($pStyles['right']);
+            }
+            if (isset($pStyles['top'])) {
+                $this->getTop()->applyFromArray($pStyles['top']);
+            }
+            if (isset($pStyles['bottom'])) {
+                $this->getBottom()->applyFromArray($pStyles['bottom']);
+            }
+            if (isset($pStyles['diagonal'])) {
+                $this->getDiagonal()->applyFromArray($pStyles['diagonal']);
+            }
+            if (isset($pStyles['diagonaldirection'])) {
+                $this->setDiagonalDirection($pStyles['diagonaldirection']);
+            }
+            if (isset($pStyles['allborders'])) {
+                $this->getLeft()->applyFromArray($pStyles['allborders']);
+                $this->getRight()->applyFromArray($pStyles['allborders']);
+                $this->getTop()->applyFromArray($pStyles['allborders']);
+                $this->getBottom()->applyFromArray($pStyles['allborders']);
+            }
         }
 
         return $this;
@@ -403,11 +399,11 @@ class Borders extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparabl
     /**
      * Set DiagonalDirection.
      *
-     * @param int $pValue
+     * @param int $pValue see self::DIAGONAL_*
      *
      * @return Borders
      */
-    public function setDiagonalDirection($pValue = self::DIAGONAL_NONE)
+    public function setDiagonalDirection($pValue)
     {
         if ($pValue == '') {
             $pValue = self::DIAGONAL_NONE;
diff --git a/src/PhpSpreadsheet/Style/Color.php b/src/PhpSpreadsheet/Style/Color.php
index 2079ba77..3fdd6308 100644
--- a/src/PhpSpreadsheet/Style/Color.php
+++ b/src/PhpSpreadsheet/Style/Color.php
@@ -152,21 +152,17 @@ class Color extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Color
      */
-    public function applyFromArray($pStyles = null)
+    public function applyFromArray(array $pStyles)
     {
-        if (is_array($pStyles)) {
-            if ($this->isSupervisor) {
-                $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
-            } else {
-                if (isset($pStyles['rgb'])) {
-                    $this->setRGB($pStyles['rgb']);
-                }
-                if (isset($pStyles['argb'])) {
-                    $this->setARGB($pStyles['argb']);
-                }
-            }
+        if ($this->isSupervisor) {
+            $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
         } else {
-            throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid style array passed.');
+            if (isset($pStyles['rgb'])) {
+                $this->setRGB($pStyles['rgb']);
+            }
+            if (isset($pStyles['argb'])) {
+                $this->setARGB($pStyles['argb']);
+            }
         }
 
         return $this;
@@ -189,11 +185,11 @@ class Color extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
     /**
      * Set ARGB.
      *
-     * @param string $pValue
+     * @param string $pValue see self::COLOR_*
      *
      * @return Color
      */
-    public function setARGB($pValue = self::COLOR_BLACK)
+    public function setARGB($pValue)
     {
         if ($pValue == '') {
             $pValue = self::COLOR_BLACK;
@@ -229,7 +225,7 @@ class Color extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Color
      */
-    public function setRGB($pValue = '000000')
+    public function setRGB($pValue)
     {
         if ($pValue == '') {
             $pValue = '000000';
diff --git a/src/PhpSpreadsheet/Style/Conditional.php b/src/PhpSpreadsheet/Style/Conditional.php
index d8d66213..84578411 100644
--- a/src/PhpSpreadsheet/Style/Conditional.php
+++ b/src/PhpSpreadsheet/Style/Conditional.php
@@ -108,11 +108,11 @@ class Conditional implements \PhpOffice\PhpSpreadsheet\IComparable
     /**
      * Set Condition type.
      *
-     * @param string $pValue Condition type
+     * @param string $pValue Condition type, see self::CONDITION_*
      *
      * @return Conditional
      */
-    public function setConditionType($pValue = self::CONDITION_NONE)
+    public function setConditionType($pValue)
     {
         $this->conditionType = $pValue;
 
@@ -132,11 +132,11 @@ class Conditional implements \PhpOffice\PhpSpreadsheet\IComparable
     /**
      * Set Operator type.
      *
-     * @param string $pValue Conditional operator type
+     * @param string $pValue Conditional operator type, see self::OPERATOR_*
      *
      * @return Conditional
      */
-    public function setOperatorType($pValue = self::OPERATOR_NONE)
+    public function setOperatorType($pValue)
     {
         $this->operatorType = $pValue;
 
@@ -160,7 +160,7 @@ class Conditional implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Conditional
      */
-    public function setText($value = null)
+    public function setText($value)
     {
         $this->text = $value;
 
@@ -201,7 +201,7 @@ class Conditional implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Conditional
      */
-    public function addCondition($pValue = '')
+    public function addCondition($pValue)
     {
         $this->condition[] = $pValue;
 
diff --git a/src/PhpSpreadsheet/Style/Fill.php b/src/PhpSpreadsheet/Style/Fill.php
index 089fa6bb..57d64f34 100644
--- a/src/PhpSpreadsheet/Style/Fill.php
+++ b/src/PhpSpreadsheet/Style/Fill.php
@@ -153,31 +153,27 @@ class Fill extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Fill
      */
-    public function applyFromArray($pStyles = null)
+    public function applyFromArray(array $pStyles)
     {
-        if (is_array($pStyles)) {
-            if ($this->isSupervisor) {
-                $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
-            } else {
-                if (isset($pStyles['type'])) {
-                    $this->setFillType($pStyles['type']);
-                }
-                if (isset($pStyles['rotation'])) {
-                    $this->setRotation($pStyles['rotation']);
-                }
-                if (isset($pStyles['startcolor'])) {
-                    $this->getStartColor()->applyFromArray($pStyles['startcolor']);
-                }
-                if (isset($pStyles['endcolor'])) {
-                    $this->getEndColor()->applyFromArray($pStyles['endcolor']);
-                }
-                if (isset($pStyles['color'])) {
-                    $this->getStartColor()->applyFromArray($pStyles['color']);
-                    $this->getEndColor()->applyFromArray($pStyles['color']);
-                }
-            }
+        if ($this->isSupervisor) {
+            $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
         } else {
-            throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid style array passed.');
+            if (isset($pStyles['type'])) {
+                $this->setFillType($pStyles['type']);
+            }
+            if (isset($pStyles['rotation'])) {
+                $this->setRotation($pStyles['rotation']);
+            }
+            if (isset($pStyles['startcolor'])) {
+                $this->getStartColor()->applyFromArray($pStyles['startcolor']);
+            }
+            if (isset($pStyles['endcolor'])) {
+                $this->getEndColor()->applyFromArray($pStyles['endcolor']);
+            }
+            if (isset($pStyles['color'])) {
+                $this->getStartColor()->applyFromArray($pStyles['color']);
+                $this->getEndColor()->applyFromArray($pStyles['color']);
+            }
         }
 
         return $this;
@@ -200,11 +196,11 @@ class Fill extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
     /**
      * Set Fill Type.
      *
-     * @param string $pValue Fill type
+     * @param string $pValue Fill type, see self::FILL_*
      *
      * @return Fill
      */
-    public function setFillType($pValue = self::FILL_NONE)
+    public function setFillType($pValue)
     {
         if ($this->isSupervisor) {
             $styleArray = $this->getStyleArray(['type' => $pValue]);
@@ -237,7 +233,7 @@ class Fill extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Fill
      */
-    public function setRotation($pValue = 0)
+    public function setRotation($pValue)
     {
         if ($this->isSupervisor) {
             $styleArray = $this->getStyleArray(['rotation' => $pValue]);
diff --git a/src/PhpSpreadsheet/Style/Font.php b/src/PhpSpreadsheet/Style/Font.php
index ba4cc7f0..b40b788b 100644
--- a/src/PhpSpreadsheet/Style/Font.php
+++ b/src/PhpSpreadsheet/Style/Font.php
@@ -178,42 +178,38 @@ class Font extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Font
      */
-    public function applyFromArray($pStyles = null)
+    public function applyFromArray(array $pStyles)
     {
-        if (is_array($pStyles)) {
-            if ($this->isSupervisor) {
-                $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
-            } else {
-                if (isset($pStyles['name'])) {
-                    $this->setName($pStyles['name']);
-                }
-                if (isset($pStyles['bold'])) {
-                    $this->setBold($pStyles['bold']);
-                }
-                if (isset($pStyles['italic'])) {
-                    $this->setItalic($pStyles['italic']);
-                }
-                if (isset($pStyles['superScript'])) {
-                    $this->setSuperScript($pStyles['superScript']);
-                }
-                if (isset($pStyles['subScript'])) {
-                    $this->setSubScript($pStyles['subScript']);
-                }
-                if (isset($pStyles['underline'])) {
-                    $this->setUnderline($pStyles['underline']);
-                }
-                if (isset($pStyles['strike'])) {
-                    $this->setStrikethrough($pStyles['strike']);
-                }
-                if (isset($pStyles['color'])) {
-                    $this->getColor()->applyFromArray($pStyles['color']);
-                }
-                if (isset($pStyles['size'])) {
-                    $this->setSize($pStyles['size']);
-                }
-            }
+        if ($this->isSupervisor) {
+            $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
         } else {
-            throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid style array passed.');
+            if (isset($pStyles['name'])) {
+                $this->setName($pStyles['name']);
+            }
+            if (isset($pStyles['bold'])) {
+                $this->setBold($pStyles['bold']);
+            }
+            if (isset($pStyles['italic'])) {
+                $this->setItalic($pStyles['italic']);
+            }
+            if (isset($pStyles['superScript'])) {
+                $this->setSuperScript($pStyles['superScript']);
+            }
+            if (isset($pStyles['subScript'])) {
+                $this->setSubScript($pStyles['subScript']);
+            }
+            if (isset($pStyles['underline'])) {
+                $this->setUnderline($pStyles['underline']);
+            }
+            if (isset($pStyles['strike'])) {
+                $this->setStrikethrough($pStyles['strike']);
+            }
+            if (isset($pStyles['color'])) {
+                $this->getColor()->applyFromArray($pStyles['color']);
+            }
+            if (isset($pStyles['size'])) {
+                $this->setSize($pStyles['size']);
+            }
         }
 
         return $this;
@@ -240,7 +236,7 @@ class Font extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Font
      */
-    public function setName($pValue = 'Calibri')
+    public function setName($pValue)
     {
         if ($pValue == '') {
             $pValue = 'Calibri';
@@ -276,7 +272,7 @@ class Font extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Font
      */
-    public function setSize($pValue = 10)
+    public function setSize($pValue)
     {
         if ($pValue == '') {
             $pValue = 10;
@@ -312,7 +308,7 @@ class Font extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Font
      */
-    public function setBold($pValue = false)
+    public function setBold($pValue)
     {
         if ($pValue == '') {
             $pValue = false;
@@ -348,7 +344,7 @@ class Font extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Font
      */
-    public function setItalic($pValue = false)
+    public function setItalic($pValue)
     {
         if ($pValue == '') {
             $pValue = false;
@@ -384,7 +380,7 @@ class Font extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Font
      */
-    public function setSuperScript($pValue = false)
+    public function setSuperScript($pValue)
     {
         if ($pValue == '') {
             $pValue = false;
@@ -421,7 +417,7 @@ class Font extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Font
      */
-    public function setSubScript($pValue = false)
+    public function setSubScript($pValue)
     {
         if ($pValue == '') {
             $pValue = false;
@@ -460,7 +456,7 @@ class Font extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Font
      */
-    public function setUnderline($pValue = self::UNDERLINE_NONE)
+    public function setUnderline($pValue)
     {
         if (is_bool($pValue)) {
             $pValue = ($pValue) ? self::UNDERLINE_SINGLE : self::UNDERLINE_NONE;
@@ -498,7 +494,7 @@ class Font extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Font
      */
-    public function setStrikethrough($pValue = false)
+    public function setStrikethrough($pValue)
     {
         if ($pValue == '') {
             $pValue = false;
diff --git a/src/PhpSpreadsheet/Style/NumberFormat.php b/src/PhpSpreadsheet/Style/NumberFormat.php
index fb729905..779fb2f9 100644
--- a/src/PhpSpreadsheet/Style/NumberFormat.php
+++ b/src/PhpSpreadsheet/Style/NumberFormat.php
@@ -155,18 +155,14 @@ class NumberFormat extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComp
      *
      * @return NumberFormat
      */
-    public function applyFromArray($pStyles = null)
+    public function applyFromArray(array $pStyles)
     {
-        if (is_array($pStyles)) {
-            if ($this->isSupervisor) {
-                $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
-            } else {
-                if (isset($pStyles['code'])) {
-                    $this->setFormatCode($pStyles['code']);
-                }
-            }
+        if ($this->isSupervisor) {
+            $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
         } else {
-            throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid style array passed.');
+            if (isset($pStyles['code'])) {
+                $this->setFormatCode($pStyles['code']);
+            }
         }
 
         return $this;
@@ -192,11 +188,11 @@ class NumberFormat extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComp
     /**
      * Set Format Code.
      *
-     * @param string $pValue
+     * @param string $pValue see self::FORMAT_*
      *
      * @return NumberFormat
      */
-    public function setFormatCode($pValue = self::FORMAT_GENERAL)
+    public function setFormatCode($pValue)
     {
         if ($pValue == '') {
             $pValue = self::FORMAT_GENERAL;
@@ -233,7 +229,7 @@ class NumberFormat extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComp
      *
      * @return NumberFormat
      */
-    public function setBuiltInFormatCode($pValue = 0)
+    public function setBuiltInFormatCode($pValue)
     {
         if ($this->isSupervisor) {
             $styleArray = $this->getStyleArray(['code' => self::builtInFormatCode($pValue)]);
@@ -588,12 +584,12 @@ class NumberFormat extends Supervisor implements \PhpOffice\PhpSpreadsheet\IComp
      * Convert a value in a pre-defined format to a PHP string.
      *
      * @param mixed $value Value to format
-     * @param string $format Format code
+     * @param string $format Format code, see = self::FORMAT_*
      * @param array $callBack Callback function for additional formatting of string
      *
      * @return string Formatted string
      */
-    public static function toFormattedString($value = '0', $format = self::FORMAT_GENERAL, $callBack = null)
+    public static function toFormattedString($value, $format, $callBack = null)
     {
         // For now we do not treat strings although section 4 of a format code affects strings
         if (!is_numeric($value)) {
diff --git a/src/PhpSpreadsheet/Style/Protection.php b/src/PhpSpreadsheet/Style/Protection.php
index 27145488..848ac1be 100644
--- a/src/PhpSpreadsheet/Style/Protection.php
+++ b/src/PhpSpreadsheet/Style/Protection.php
@@ -108,21 +108,17 @@ class Protection extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompar
      *
      * @return Protection
      */
-    public function applyFromArray($pStyles = null)
+    public function applyFromArray(array $pStyles)
     {
-        if (is_array($pStyles)) {
-            if ($this->isSupervisor) {
-                $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
-            } else {
-                if (isset($pStyles['locked'])) {
-                    $this->setLocked($pStyles['locked']);
-                }
-                if (isset($pStyles['hidden'])) {
-                    $this->setHidden($pStyles['hidden']);
-                }
-            }
+        if ($this->isSupervisor) {
+            $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($this->getStyleArray($pStyles));
         } else {
-            throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid style array passed.');
+            if (isset($pStyles['locked'])) {
+                $this->setLocked($pStyles['locked']);
+            }
+            if (isset($pStyles['hidden'])) {
+                $this->setHidden($pStyles['hidden']);
+            }
         }
 
         return $this;
@@ -145,11 +141,11 @@ class Protection extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompar
     /**
      * Set locked.
      *
-     * @param string $pValue
+     * @param string $pValue see self::PROTECTION_*
      *
      * @return Protection
      */
-    public function setLocked($pValue = self::PROTECTION_INHERIT)
+    public function setLocked($pValue)
     {
         if ($this->isSupervisor) {
             $styleArray = $this->getStyleArray(['locked' => $pValue]);
@@ -178,11 +174,11 @@ class Protection extends Supervisor implements \PhpOffice\PhpSpreadsheet\ICompar
     /**
      * Set hidden.
      *
-     * @param string $pValue
+     * @param string $pValue see self::PROTECTION_*
      *
      * @return Protection
      */
-    public function setHidden($pValue = self::PROTECTION_INHERIT)
+    public function setHidden($pValue)
     {
         if ($this->isSupervisor) {
             $styleArray = $this->getStyleArray(['hidden' => $pValue]);
diff --git a/src/PhpSpreadsheet/Worksheet.php b/src/PhpSpreadsheet/Worksheet.php
index 002e929a..7565c854 100644
--- a/src/PhpSpreadsheet/Worksheet.php
+++ b/src/PhpSpreadsheet/Worksheet.php
@@ -582,7 +582,7 @@ class Worksheet implements IComparable
      *
      * @return false|Chart
      */
-    public function getChartByIndex($index = null)
+    public function getChartByIndex($index)
     {
         $chartCount = count($this->chartCollection);
         if ($chartCount == 0) {
@@ -624,7 +624,7 @@ class Worksheet implements IComparable
      *
      * @return false|Chart
      */
-    public function getChartByName($chartName = '')
+    public function getChartByName($chartName)
     {
         $chartCount = count($this->chartCollection);
         if ($chartCount == 0) {
@@ -833,7 +833,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setTitle($pValue = 'Worksheet', $updateFormulaCellReferences = true)
+    public function setTitle($pValue, $updateFormulaCellReferences = true)
     {
         // Is this a 'rename' or not?
         if ($this->getTitle() == $pValue) {
@@ -908,7 +908,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setSheetState($value = self::SHEETSTATE_VISIBLE)
+    public function setSheetState($value)
     {
         $this->sheetState = $value;
 
@@ -1109,17 +1109,16 @@ class Worksheet implements IComparable
     /**
      * Set a cell value.
      *
-     * @param string $pCoordinate Coordinate of the cell
+     * @param string $pCoordinate Coordinate of the cell, eg: 'A1'
      * @param mixed $pValue Value of the cell
-     * @param bool $returnCell Return the worksheet (false, default) or the cell (true)
      *
-     * @return Worksheet|Cell Depending on the last parameter being specified
+     * @return Worksheet
      */
-    public function setCellValue($pCoordinate = 'A1', $pValue = null, $returnCell = false)
+    public function setCellValue($pCoordinate, $pValue)
     {
-        $cell = $this->getCell(strtoupper($pCoordinate))->setValue($pValue);
+        $this->getCell($pCoordinate)->setValue($pValue);
 
-        return ($returnCell) ? $cell : $this;
+        return $this;
     }
 
     /**
@@ -1128,57 +1127,55 @@ class Worksheet implements IComparable
      * @param int $pColumn Numeric column coordinate of the cell (A = 0)
      * @param int $pRow Numeric row coordinate of the cell
      * @param mixed $pValue Value of the cell
-     * @param bool $returnCell Return the worksheet (false, default) or the cell (true)
      *
-     * @return Worksheet|Cell Depending on the last parameter being specified
+     * @return Worksheet
      */
-    public function setCellValueByColumnAndRow($pColumn = 0, $pRow = 1, $pValue = null, $returnCell = false)
+    public function setCellValueByColumnAndRow($pColumn, $pRow, $pValue)
     {
-        $cell = $this->getCellByColumnAndRow($pColumn, $pRow)->setValue($pValue);
+        $this->getCellByColumnAndRow($pColumn, $pRow)->setValue($pValue);
 
-        return ($returnCell) ? $cell : $this;
+        return $this;
     }
 
     /**
      * Set a cell value.
      *
-     * @param string $pCoordinate Coordinate of the cell
+     * @param string $pCoordinate Coordinate of the cell, eg: 'A1'
      * @param mixed $pValue Value of the cell
-     * @param string $pDataType Explicit data type
-     * @param bool $returnCell Return the worksheet (false, default) or the cell (true)
+     * @param string $pDataType Explicit data type, see Cell\DataType::TYPE_*
      *
-     * @return Worksheet|Cell Depending on the last parameter being specified
+     * @return Worksheet
      */
-    public function setCellValueExplicit($pCoordinate = 'A1', $pValue = null, $pDataType = Cell\DataType::TYPE_STRING, $returnCell = false)
+    public function setCellValueExplicit($pCoordinate, $pValue, $pDataType)
     {
         // Set value
-        $cell = $this->getCell(strtoupper($pCoordinate))->setValueExplicit($pValue, $pDataType);
+        $this->getCell($pCoordinate)->setValueExplicit($pValue, $pDataType);
 
-        return ($returnCell) ? $cell : $this;
+        return $this;
     }
 
     /**
      * Set a cell value by using numeric cell coordinates.
      *
-     * @param int $pColumn Numeric column coordinate of the cell
+     * @param int $pColumn Numeric column coordinate of the cell (A = 0)
      * @param int $pRow Numeric row coordinate of the cell
      * @param mixed $pValue Value of the cell
-     * @param string $pDataType Explicit data type
+     * @param string $pDataType Explicit data type, see Cell\DataType::TYPE_*
      * @param bool $returnCell Return the worksheet (false, default) or the cell (true)
      *
-     * @return Worksheet|Cell Depending on the last parameter being specified
+     * @return Worksheet
      */
-    public function setCellValueExplicitByColumnAndRow($pColumn = 0, $pRow = 1, $pValue = null, $pDataType = Cell\DataType::TYPE_STRING, $returnCell = false)
+    public function setCellValueExplicitByColumnAndRow($pColumn, $pRow, $pValue, $pDataType)
     {
-        $cell = $this->getCellByColumnAndRow($pColumn, $pRow)->setValueExplicit($pValue, $pDataType);
+        $this->getCellByColumnAndRow($pColumn, $pRow)->setValueExplicit($pValue, $pDataType);
 
-        return ($returnCell) ? $cell : $this;
+        return $this;
     }
 
     /**
      * Get cell at a specific coordinate.
      *
-     * @param string $pCoordinate Coordinate of the cell
+     * @param string $pCoordinate Coordinate of the cell, eg: 'A1'
      * @param bool $createIfNotExists Flag indicating whether a new cell should be created if it doesn't
      *                                       already exist, or a null should be returned instead
      *
@@ -1186,7 +1183,7 @@ class Worksheet implements IComparable
      *
      * @return null|Cell Cell that was found/created or null
      */
-    public function getCell($pCoordinate = 'A1', $createIfNotExists = true)
+    public function getCell($pCoordinate, $createIfNotExists = true)
     {
         // Check cell collection
         if ($this->cellCollection->has(strtoupper($pCoordinate))) {
@@ -1234,7 +1231,7 @@ class Worksheet implements IComparable
      *
      * @return null|Cell Cell that was found/created or null
      */
-    public function getCellByColumnAndRow($pColumn = 0, $pRow = 1, $createIfNotExists = true)
+    public function getCellByColumnAndRow($pColumn, $pRow, $createIfNotExists = true)
     {
         $columnLetter = Cell::stringFromColumnIndex($pColumn);
         $coordinate = $columnLetter . $pRow;
@@ -1286,13 +1283,13 @@ class Worksheet implements IComparable
     /**
      * Does the cell at a specific coordinate exist?
      *
-     * @param string $pCoordinate Coordinate of the cell
+     * @param string $pCoordinate Coordinate of the cell eg: 'A1'
      *
      * @throws Exception
      *
      * @return bool
      */
-    public function cellExists($pCoordinate = 'A1')
+    public function cellExists($pCoordinate)
     {
         // Worksheet reference?
         if (strpos($pCoordinate, '!') !== false) {
@@ -1336,12 +1333,12 @@ class Worksheet implements IComparable
     /**
      * Cell at a specific coordinate by using numeric cell coordinates exists?
      *
-     * @param string $pColumn Numeric column coordinate of the cell
+     * @param string $pColumn Numeric column coordinate of the cell (A = 0)
      * @param string $pRow Numeric row coordinate of the cell
      *
      * @return bool
      */
-    public function cellExistsByColumnAndRow($pColumn = 0, $pRow = 1)
+    public function cellExistsByColumnAndRow($pColumn, $pRow)
     {
         return $this->cellExists(Cell::stringFromColumnIndex($pColumn) . $pRow);
     }
@@ -1354,7 +1351,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet\RowDimension
      */
-    public function getRowDimension($pRow = 1, $create = true)
+    public function getRowDimension($pRow, $create = true)
     {
         // Found
         $found = null;
@@ -1375,12 +1372,12 @@ class Worksheet implements IComparable
     /**
      * Get column dimension at a specific column.
      *
-     * @param string $pColumn String index of the column
+     * @param string $pColumn String index of the column eg: 'A'
      * @param mixed $create
      *
      * @return Worksheet\ColumnDimension
      */
-    public function getColumnDimension($pColumn = 'A', $create = true)
+    public function getColumnDimension($pColumn, $create = true)
     {
         // Uppercase coordinate
         $pColumn = strtoupper($pColumn);
@@ -1403,11 +1400,11 @@ class Worksheet implements IComparable
     /**
      * Get column dimension at a specific column by using numeric cell coordinates.
      *
-     * @param int $pColumn Numeric column coordinate of the cell
+     * @param int $pColumn Numeric column coordinate of the cell (A = 0)
      *
      * @return Worksheet\ColumnDimension
      */
-    public function getColumnDimensionByColumn($pColumn = 0)
+    public function getColumnDimensionByColumn($pColumn)
     {
         return $this->getColumnDimension(Cell::stringFromColumnIndex($pColumn));
     }
@@ -1425,13 +1422,13 @@ class Worksheet implements IComparable
     /**
      * Get style for cell.
      *
-     * @param string $pCellCoordinate Cell coordinate (or range) to get style for
+     * @param string $pCellCoordinate Cell coordinate (or range) to get style for, eg: 'A1'
      *
      * @throws Exception
      *
      * @return Style
      */
-    public function getStyle($pCellCoordinate = 'A1')
+    public function getStyle($pCellCoordinate)
     {
         // set this sheet as active
         $this->parent->setActiveSheetIndex($this->parent->getIndex($this));
@@ -1445,11 +1442,11 @@ class Worksheet implements IComparable
     /**
      * Get conditional styles for a cell.
      *
-     * @param string $pCoordinate
+     * @param string $pCoordinate eg: 'A1'
      *
      * @return Style\Conditional[]
      */
-    public function getConditionalStyles($pCoordinate = 'A1')
+    public function getConditionalStyles($pCoordinate)
     {
         $pCoordinate = strtoupper($pCoordinate);
         if (!isset($this->conditionalStylesCollection[$pCoordinate])) {
@@ -1462,11 +1459,11 @@ class Worksheet implements IComparable
     /**
      * Do conditional styles exist for this cell?
      *
-     * @param string $pCoordinate
+     * @param string $pCoordinate eg: 'A1'
      *
      * @return bool
      */
-    public function conditionalStylesExists($pCoordinate = 'A1')
+    public function conditionalStylesExists($pCoordinate)
     {
         if (isset($this->conditionalStylesCollection[strtoupper($pCoordinate)])) {
             return true;
@@ -1478,11 +1475,11 @@ class Worksheet implements IComparable
     /**
      * Removes conditional styles for a cell.
      *
-     * @param string $pCoordinate
+     * @param string $pCoordinate eg: 'A1'
      *
      * @return Worksheet
      */
-    public function removeConditionalStyles($pCoordinate = 'A1')
+    public function removeConditionalStyles($pCoordinate)
     {
         unset($this->conditionalStylesCollection[strtoupper($pCoordinate)]);
 
@@ -1517,16 +1514,16 @@ class Worksheet implements IComparable
     /**
      * Get style for cell by using numeric cell coordinates.
      *
-     * @param int $pColumn Numeric column coordinate of the cell
+     * @param int $pColumn Numeric column coordinate of the cell (A = 0)
      * @param int $pRow Numeric row coordinate of the cell
-     * @param int pColumn2 Numeric column coordinate of the range cell
+     * @param int pColumn2 Numeric column coordinate of the range cell (A = 0)
      * @param int pRow2 Numeric row coordinate of the range cell
      * @param null|mixed $pColumn2
      * @param null|mixed $pRow2
      *
      * @return Style
      */
-    public function getStyleByColumnAndRow($pColumn = 0, $pRow = 1, $pColumn2 = null, $pRow2 = null)
+    public function getStyleByColumnAndRow($pColumn, $pRow, $pColumn2 = null, $pRow2 = null)
     {
         if (!is_null($pColumn2) && !is_null($pRow2)) {
             $cellRange = Cell::stringFromColumnIndex($pColumn) . $pRow . ':' . Cell::stringFromColumnIndex($pColumn2) . $pRow2;
@@ -1628,25 +1625,25 @@ class Worksheet implements IComparable
     /**
      * Set break on a cell.
      *
-     * @param string $pCell Cell coordinate (e.g. A1)
+     * @param string $pCoordinate Cell coordinate (e.g. A1)
      * @param int $pBreak Break type (type of Worksheet::BREAK_*)
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function setBreak($pCell = 'A1', $pBreak = self::BREAK_NONE)
+    public function setBreak($pCoordinate, $pBreak)
     {
         // Uppercase coordinate
-        $pCell = strtoupper($pCell);
+        $pCoordinate = strtoupper($pCoordinate);
 
-        if ($pCell != '') {
+        if ($pCoordinate != '') {
             if ($pBreak == self::BREAK_NONE) {
-                if (isset($this->breaks[$pCell])) {
-                    unset($this->breaks[$pCell]);
+                if (isset($this->breaks[$pCoordinate])) {
+                    unset($this->breaks[$pCoordinate]);
                 }
             } else {
-                $this->breaks[$pCell] = $pBreak;
+                $this->breaks[$pCoordinate] = $pBreak;
             }
         } else {
             throw new Exception('No cell coordinate specified.');
@@ -1658,13 +1655,13 @@ class Worksheet implements IComparable
     /**
      * Set break on a cell by using numeric cell coordinates.
      *
-     * @param int $pColumn Numeric column coordinate of the cell
+     * @param int $pColumn Numeric column coordinate of the cell (A = 0)
      * @param int $pRow Numeric row coordinate of the cell
      * @param int $pBreak Break type (type of \PhpOffice\PhpSpreadsheet\Worksheet::BREAK_*)
      *
      * @return Worksheet
      */
-    public function setBreakByColumnAndRow($pColumn = 0, $pRow = 1, $pBreak = self::BREAK_NONE)
+    public function setBreakByColumnAndRow($pColumn, $pRow, $pBreak)
     {
         return $this->setBreak(Cell::stringFromColumnIndex($pColumn) . $pRow, $pBreak);
     }
@@ -1688,7 +1685,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function mergeCells($pRange = 'A1:A1')
+    public function mergeCells($pRange)
     {
         // Uppercase coordinate
         $pRange = strtoupper($pRange);
@@ -1724,16 +1721,16 @@ class Worksheet implements IComparable
     /**
      * Set merge on a cell range by using numeric cell coordinates.
      *
-     * @param int $pColumn1 Numeric column coordinate of the first cell
+     * @param int $pColumn1 Numeric column coordinate of the first cell (A = 0)
      * @param int $pRow1 Numeric row coordinate of the first cell
-     * @param int $pColumn2 Numeric column coordinate of the last cell
+     * @param int $pColumn2 Numeric column coordinate of the last cell (A = 0)
      * @param int $pRow2 Numeric row coordinate of the last cell
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function mergeCellsByColumnAndRow($pColumn1 = 0, $pRow1 = 1, $pColumn2 = 0, $pRow2 = 1)
+    public function mergeCellsByColumnAndRow($pColumn1, $pRow1, $pColumn2, $pRow2)
     {
         $cellRange = Cell::stringFromColumnIndex($pColumn1) . $pRow1 . ':' . Cell::stringFromColumnIndex($pColumn2) . $pRow2;
 
@@ -1749,7 +1746,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function unmergeCells($pRange = 'A1:A1')
+    public function unmergeCells($pRange)
     {
         // Uppercase coordinate
         $pRange = strtoupper($pRange);
@@ -1770,16 +1767,16 @@ class Worksheet implements IComparable
     /**
      * Remove merge on a cell range by using numeric cell coordinates.
      *
-     * @param int $pColumn1 Numeric column coordinate of the first cell
+     * @param int $pColumn1 Numeric column coordinate of the first cell (A = 0)
      * @param int $pRow1 Numeric row coordinate of the first cell
-     * @param int $pColumn2 Numeric column coordinate of the last cell
+     * @param int $pColumn2 Numeric column coordinate of the last cell (A = 0)
      * @param int $pRow2 Numeric row coordinate of the last cell
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function unmergeCellsByColumnAndRow($pColumn1 = 0, $pRow1 = 1, $pColumn2 = 0, $pRow2 = 1)
+    public function unmergeCellsByColumnAndRow($pColumn1, $pRow1, $pColumn2, $pRow2)
     {
         $cellRange = Cell::stringFromColumnIndex($pColumn1) . $pRow1 . ':' . Cell::stringFromColumnIndex($pColumn2) . $pRow2;
 
@@ -1803,7 +1800,7 @@ class Worksheet implements IComparable
      * @param array
      * @param mixed $pValue
      */
-    public function setMergeCells($pValue = [])
+    public function setMergeCells(array $pValue)
     {
         $this->mergeCells = $pValue;
 
@@ -1821,7 +1818,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function protectCells($pRange = 'A1', $pPassword = '', $pAlreadyHashed = false)
+    public function protectCells($pRange, $pPassword, $pAlreadyHashed = false)
     {
         // Uppercase coordinate
         $pRange = strtoupper($pRange);
@@ -1837,9 +1834,9 @@ class Worksheet implements IComparable
     /**
      * Set protection on a cell range by using numeric cell coordinates.
      *
-     * @param int $pColumn1 Numeric column coordinate of the first cell
+     * @param int $pColumn1 Numeric column coordinate of the first cell (A = 0)
      * @param int $pRow1 Numeric row coordinate of the first cell
-     * @param int $pColumn2 Numeric column coordinate of the last cell
+     * @param int $pColumn2 Numeric column coordinate of the last cell (A = 0)
      * @param int $pRow2 Numeric row coordinate of the last cell
      * @param string $pPassword Password to unlock the protection
      * @param bool $pAlreadyHashed If the password has already been hashed, set this to true
@@ -1848,7 +1845,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function protectCellsByColumnAndRow($pColumn1 = 0, $pRow1 = 1, $pColumn2 = 0, $pRow2 = 1, $pPassword = '', $pAlreadyHashed = false)
+    public function protectCellsByColumnAndRow($pColumn1, $pRow1, $pColumn2, $pRow2, $pPassword, $pAlreadyHashed = false)
     {
         $cellRange = Cell::stringFromColumnIndex($pColumn1) . $pRow1 . ':' . Cell::stringFromColumnIndex($pColumn2) . $pRow2;
 
@@ -1864,7 +1861,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function unprotectCells($pRange = 'A1')
+    public function unprotectCells($pRange)
     {
         // Uppercase coordinate
         $pRange = strtoupper($pRange);
@@ -1881,9 +1878,9 @@ class Worksheet implements IComparable
     /**
      * Remove protection on a cell range by using numeric cell coordinates.
      *
-     * @param int $pColumn1 Numeric column coordinate of the first cell
+     * @param int $pColumn1 Numeric column coordinate of the first cell (A = 0)
      * @param int $pRow1 Numeric row coordinate of the first cell
-     * @param int $pColumn2 Numeric column coordinate of the last cell
+     * @param int $pColumn2 Numeric column coordinate of the last cell (A = 0)
      * @param int $pRow2 Numeric row coordinate of the last cell
      * @param string $pPassword Password to unlock the protection
      * @param bool $pAlreadyHashed If the password has already been hashed, set this to true
@@ -1892,7 +1889,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function unprotectCellsByColumnAndRow($pColumn1 = 0, $pRow1 = 1, $pColumn2 = 0, $pRow2 = 1, $pPassword = '', $pAlreadyHashed = false)
+    public function unprotectCellsByColumnAndRow($pColumn1, $pRow1, $pColumn2, $pRow2, $pPassword, $pAlreadyHashed = false)
     {
         $cellRange = Cell::stringFromColumnIndex($pColumn1) . $pRow1 . ':' . Cell::stringFromColumnIndex($pColumn2) . $pRow2;
 
@@ -1944,16 +1941,16 @@ class Worksheet implements IComparable
     /**
      * Set Autofilter Range by using numeric cell coordinates.
      *
-     * @param int $pColumn1 Numeric column coordinate of the first cell
+     * @param int $pColumn1 Numeric column coordinate of the first cell (A = 0)
      * @param int $pRow1 Numeric row coordinate of the first cell
-     * @param int $pColumn2 Numeric column coordinate of the second cell
+     * @param int $pColumn2 Numeric column coordinate of the second cell (A = 0)
      * @param int $pRow2 Numeric row coordinate of the second cell
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function setAutoFilterByColumnAndRow($pColumn1 = 0, $pRow1 = 1, $pColumn2 = 0, $pRow2 = 1)
+    public function setAutoFilterByColumnAndRow($pColumn1, $pRow1, $pColumn2, $pRow2)
     {
         return $this->setAutoFilter(
             Cell::stringFromColumnIndex($pColumn1) . $pRow1
@@ -1998,7 +1995,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function freezePane($pCell = '')
+    public function freezePane($pCell)
     {
         // Uppercase coordinate
         $pCell = strtoupper($pCell);
@@ -2014,14 +2011,14 @@ class Worksheet implements IComparable
     /**
      * Freeze Pane by using numeric cell coordinates.
      *
-     * @param int $pColumn Numeric column coordinate of the cell
+     * @param int $pColumn Numeric column coordinate of the cell (A = 0)
      * @param int $pRow Numeric row coordinate of the cell
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function freezePaneByColumnAndRow($pColumn = 0, $pRow = 1)
+    public function freezePaneByColumnAndRow($pColumn, $pRow)
     {
         return $this->freezePane(Cell::stringFromColumnIndex($pColumn) . $pRow);
     }
@@ -2046,7 +2043,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function insertNewRowBefore($pBefore = 1, $pNumRows = 1)
+    public function insertNewRowBefore($pBefore, $pNumRows = 1)
     {
         if ($pBefore >= 1) {
             $objReferenceHelper = ReferenceHelper::getInstance();
@@ -2061,14 +2058,14 @@ class Worksheet implements IComparable
     /**
      * Insert a new column, updating all possible related data.
      *
-     * @param int $pBefore Insert before this one
+     * @param int $pBefore Insert before this one, eg: 'A'
      * @param int $pNumCols Number of columns to insert
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function insertNewColumnBefore($pBefore = 'A', $pNumCols = 1)
+    public function insertNewColumnBefore($pBefore, $pNumCols = 1)
     {
         if (!is_numeric($pBefore)) {
             $objReferenceHelper = ReferenceHelper::getInstance();
@@ -2083,14 +2080,14 @@ class Worksheet implements IComparable
     /**
      * Insert a new column, updating all possible related data.
      *
-     * @param int $pBefore Insert before this one (numeric column coordinate of the cell)
+     * @param int $pBefore Insert before this one (numeric column coordinate of the cell, A = 0)
      * @param int $pNumCols Number of columns to insert
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function insertNewColumnBeforeByIndex($pBefore = 0, $pNumCols = 1)
+    public function insertNewColumnBeforeByIndex($pBefore, $pNumCols = 1)
     {
         if ($pBefore >= 0) {
             return $this->insertNewColumnBefore(Cell::stringFromColumnIndex($pBefore), $pNumCols);
@@ -2108,7 +2105,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function removeRow($pRow = 1, $pNumRows = 1)
+    public function removeRow($pRow, $pNumRows = 1)
     {
         if ($pRow >= 1) {
             $highestRow = $this->getHighestDataRow();
@@ -2128,14 +2125,14 @@ class Worksheet implements IComparable
     /**
      * Remove a column, updating all possible related data.
      *
-     * @param string $pColumn Remove starting with this one
+     * @param string $pColumn Remove starting with this one, eg: 'A'
      * @param int $pNumCols Number of columns to remove
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function removeColumn($pColumn = 'A', $pNumCols = 1)
+    public function removeColumn($pColumn, $pNumCols = 1)
     {
         if (!is_numeric($pColumn)) {
             $highestColumn = $this->getHighestDataColumn();
@@ -2156,14 +2153,14 @@ class Worksheet implements IComparable
     /**
      * Remove a column, updating all possible related data.
      *
-     * @param int $pColumn Remove starting with this one (numeric column coordinate of the cell)
+     * @param int $pColumn Remove starting with this one (numeric column coordinate of the cell A = 0)
      * @param int $pNumCols Number of columns to remove
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function removeColumnByIndex($pColumn = 0, $pNumCols = 1)
+    public function removeColumnByIndex($pColumn, $pNumCols = 1)
     {
         if ($pColumn >= 0) {
             return $this->removeColumn(Cell::stringFromColumnIndex($pColumn), $pNumCols);
@@ -2188,7 +2185,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setShowGridlines($pValue = false)
+    public function setShowGridlines($pValue)
     {
         $this->showGridlines = $pValue;
 
@@ -2212,7 +2209,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setPrintGridlines($pValue = false)
+    public function setPrintGridlines($pValue)
     {
         $this->printGridlines = $pValue;
 
@@ -2236,7 +2233,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setShowRowColHeaders($pValue = false)
+    public function setShowRowColHeaders($pValue)
     {
         $this->showRowColHeaders = $pValue;
 
@@ -2260,7 +2257,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setShowSummaryBelow($pValue = true)
+    public function setShowSummaryBelow($pValue)
     {
         $this->showSummaryBelow = $pValue;
 
@@ -2284,7 +2281,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setShowSummaryRight($pValue = true)
+    public function setShowSummaryRight($pValue)
     {
         $this->showSummaryRight = $pValue;
 
@@ -2309,7 +2306,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setComments($pValue = [])
+    public function setComments(array $pValue)
     {
         $this->comments = $pValue;
 
@@ -2319,13 +2316,13 @@ class Worksheet implements IComparable
     /**
      * Get comment for cell.
      *
-     * @param string $pCellCoordinate Cell coordinate to get comment for
+     * @param string $pCellCoordinate Cell coordinate to get comment for, eg: 'A1'
      *
      * @throws Exception
      *
      * @return Comment
      */
-    public function getComment($pCellCoordinate = 'A1')
+    public function getComment($pCellCoordinate)
     {
         // Uppercase coordinate
         $pCellCoordinate = strtoupper($pCellCoordinate);
@@ -2353,12 +2350,12 @@ class Worksheet implements IComparable
     /**
      * Get comment for cell by using numeric cell coordinates.
      *
-     * @param int $pColumn Numeric column coordinate of the cell
+     * @param int $pColumn Numeric column coordinate of the cell (A = 0)
      * @param int $pRow Numeric row coordinate of the cell
      *
      * @return Comment
      */
-    public function getCommentByColumnAndRow($pColumn = 0, $pRow = 1)
+    public function getCommentByColumnAndRow($pColumn, $pRow)
     {
         return $this->getComment(Cell::stringFromColumnIndex($pColumn) . $pRow);
     }
@@ -2390,7 +2387,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setSelectedCell($pCoordinate = 'A1')
+    public function setSelectedCell($pCoordinate)
     {
         return $this->setSelectedCells($pCoordinate);
     }
@@ -2404,7 +2401,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setSelectedCells($pCoordinate = 'A1')
+    public function setSelectedCells($pCoordinate)
     {
         // Uppercase coordinate
         $pCoordinate = strtoupper($pCoordinate);
@@ -2435,14 +2432,14 @@ class Worksheet implements IComparable
     /**
      * Selected cell by using numeric cell coordinates.
      *
-     * @param int $pColumn Numeric column coordinate of the cell
+     * @param int $pColumn Numeric column coordinate of the cell (A = 0)
      * @param int $pRow Numeric row coordinate of the cell
      *
      * @throws Exception
      *
      * @return Worksheet
      */
-    public function setSelectedCellByColumnAndRow($pColumn = 0, $pRow = 1)
+    public function setSelectedCellByColumnAndRow($pColumn, $pRow)
     {
         return $this->setSelectedCells(Cell::stringFromColumnIndex($pColumn) . $pRow);
     }
@@ -2464,7 +2461,7 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function setRightToLeft($value = false)
+    public function setRightToLeft($value)
     {
         $this->rightToLeft = $value;
 
@@ -2483,38 +2480,34 @@ class Worksheet implements IComparable
      *
      * @return Worksheet
      */
-    public function fromArray($source = null, $nullValue = null, $startCell = 'A1', $strictNullComparison = false)
+    public function fromArray(array $source, $nullValue = null, $startCell = 'A1', $strictNullComparison = false)
     {
-        if (is_array($source)) {
-            //    Convert a 1-D array to 2-D (for ease of looping)
-            if (!is_array(end($source))) {
-                $source = [$source];
-            }
+        //    Convert a 1-D array to 2-D (for ease of looping)
+        if (!is_array(end($source))) {
+            $source = [$source];
+        }
 
-            // start coordinate
-            list($startColumn, $startRow) = Cell::coordinateFromString($startCell);
+        // start coordinate
+        list($startColumn, $startRow) = Cell::coordinateFromString($startCell);
 
-            // Loop through $source
-            foreach ($source as $rowData) {
-                $currentColumn = $startColumn;
-                foreach ($rowData as $cellValue) {
-                    if ($strictNullComparison) {
-                        if ($cellValue !== $nullValue) {
-                            // Set cell value
-                            $this->getCell($currentColumn . $startRow)->setValue($cellValue);
-                        }
-                    } else {
-                        if ($cellValue != $nullValue) {
-                            // Set cell value
-                            $this->getCell($currentColumn . $startRow)->setValue($cellValue);
-                        }
+        // Loop through $source
+        foreach ($source as $rowData) {
+            $currentColumn = $startColumn;
+            foreach ($rowData as $cellValue) {
+                if ($strictNullComparison) {
+                    if ($cellValue !== $nullValue) {
+                        // Set cell value
+                        $this->getCell($currentColumn . $startRow)->setValue($cellValue);
+                    }
+                } else {
+                    if ($cellValue != $nullValue) {
+                        // Set cell value
+                        $this->getCell($currentColumn . $startRow)->setValue($cellValue);
                     }
-                    ++$currentColumn;
                 }
-                ++$startRow;
+                ++$currentColumn;
             }
-        } else {
-            throw new Exception('Parameter $source should be an array.');
+            ++$startRow;
         }
 
         return $this;
@@ -2532,7 +2525,7 @@ class Worksheet implements IComparable
      *
      * @return array
      */
-    public function rangeToArray($pRange = 'A1', $nullValue = null, $calculateFormulas = true, $formatData = true, $returnCellRef = false)
+    public function rangeToArray($pRange, $nullValue = null, $calculateFormulas = true, $formatData = true, $returnCellRef = false)
     {
         // Returnvalue
         $returnValue = [];
@@ -2604,7 +2597,7 @@ class Worksheet implements IComparable
      *
      * @return array
      */
-    public function namedRangeToArray($pNamedRange = '', $nullValue = null, $calculateFormulas = true, $formatData = true, $returnCellRef = false)
+    public function namedRangeToArray($pNamedRange, $nullValue = null, $calculateFormulas = true, $formatData = true, $returnCellRef = false)
     {
         $namedRange = NamedRange::resolveRange($pNamedRange, $this);
         if ($namedRange !== null) {
@@ -2746,9 +2739,9 @@ class Worksheet implements IComparable
     /**
      * Get hyperlink.
      *
-     * @param string $pCellCoordinate Cell coordinate to get hyperlink for
+     * @param string $pCellCoordinate Cell coordinate to get hyperlink for, eg: 'A1'
      */
-    public function getHyperlink($pCellCoordinate = 'A1')
+    public function getHyperlink($pCellCoordinate)
     {
         // return hyperlink if we already have one
         if (isset($this->hyperlinkCollection[$pCellCoordinate])) {
@@ -2762,14 +2755,14 @@ class Worksheet implements IComparable
     }
 
     /**
-     * Set hyperlnk.
+     * Set hyperlink.
      *
-     * @param string $pCellCoordinate Cell coordinate to insert hyperlink
-     * @param Cell\Hyperlink $pHyperlink
+     * @param string $pCellCoordinate Cell coordinate to insert hyperlink, eg: 'A1'
+     * @param Cell\Hyperlink|null $pHyperlink
      *
      * @return Worksheet
      */
-    public function setHyperlink($pCellCoordinate = 'A1', Cell\Hyperlink $pHyperlink = null)
+    public function setHyperlink($pCellCoordinate, Cell\Hyperlink $pHyperlink = null)
     {
         if ($pHyperlink === null) {
             unset($this->hyperlinkCollection[$pCellCoordinate]);
@@ -2783,11 +2776,11 @@ class Worksheet implements IComparable
     /**
      * Hyperlink at a specific coordinate exists?
      *
-     * @param string $pCoordinate
+     * @param string $pCoordinate eg: 'A1'
      *
      * @return bool
      */
-    public function hyperlinkExists($pCoordinate = 'A1')
+    public function hyperlinkExists($pCoordinate)
     {
         return isset($this->hyperlinkCollection[$pCoordinate]);
     }
@@ -2805,9 +2798,9 @@ class Worksheet implements IComparable
     /**
      * Get data validation.
      *
-     * @param string $pCellCoordinate Cell coordinate to get data validation for
+     * @param string $pCellCoordinate Cell coordinate to get data validation for, eg: 'A1'
      */
-    public function getDataValidation($pCellCoordinate = 'A1')
+    public function getDataValidation($pCellCoordinate)
     {
         // return data validation if we already have one
         if (isset($this->dataValidationCollection[$pCellCoordinate])) {
@@ -2823,12 +2816,12 @@ class Worksheet implements IComparable
     /**
      * Set data validation.
      *
-     * @param string $pCellCoordinate Cell coordinate to insert data validation
-     * @param Cell\DataValidation $pDataValidation
+     * @param string $pCellCoordinate Cell coordinate to insert data validation, eg: 'A1'
+     * @param Cell\DataValidation|null $pDataValidation
      *
      * @return Worksheet
      */
-    public function setDataValidation($pCellCoordinate = 'A1', Cell\DataValidation $pDataValidation = null)
+    public function setDataValidation($pCellCoordinate, Cell\DataValidation $pDataValidation = null)
     {
         if ($pDataValidation === null) {
             unset($this->dataValidationCollection[$pCellCoordinate]);
@@ -2842,11 +2835,11 @@ class Worksheet implements IComparable
     /**
      * Data validation at a specific coordinate exists?
      *
-     * @param string $pCoordinate
+     * @param string $pCoordinate eg: 'A1'
      *
      * @return bool
      */
-    public function dataValidationExists($pCoordinate = 'A1')
+    public function dataValidationExists($pCoordinate)
     {
         return isset($this->dataValidationCollection[$pCoordinate]);
     }
@@ -2990,7 +2983,7 @@ class Worksheet implements IComparable
      *
      * @return objWorksheet
      */
-    public function setCodeName($pValue = null)
+    public function setCodeName($pValue)
     {
         // Is this a 'rename' or not?
         if ($this->getCodeName() == $pValue) {
diff --git a/src/PhpSpreadsheet/Worksheet/AutoFilter.php b/src/PhpSpreadsheet/Worksheet/AutoFilter.php
index fd9904c8..a9298433 100644
--- a/src/PhpSpreadsheet/Worksheet/AutoFilter.php
+++ b/src/PhpSpreadsheet/Worksheet/AutoFilter.php
@@ -102,7 +102,7 @@ class AutoFilter
      *
      * @return AutoFilter
      */
-    public function setRange($pRange = '')
+    public function setRange($pRange)
     {
         // Uppercase coordinate
         $cellAddress = explode('!', strtoupper($pRange));
@@ -214,7 +214,7 @@ class AutoFilter
      *
      * @return AutoFilter\Column
      */
-    public function getColumnByOffset($pColumnOffset = 0)
+    public function getColumnByOffset($pColumnOffset)
     {
         list($rangeStart, $rangeEnd) = \PhpOffice\PhpSpreadsheet\Cell::rangeBoundaries($this->range);
         $pColumn = \PhpOffice\PhpSpreadsheet\Cell::stringFromColumnIndex($rangeStart[0] + $pColumnOffset - 1);
@@ -278,7 +278,7 @@ class AutoFilter
      * Shift an AutoFilter Column Rule to a different column.
      *
      * Note: This method bypasses validation of the destination column to ensure it is within this AutoFilter range.
-     *        Nor does it verify whether any column rule already exists at $toColumn, but will simply overrideany existing value.
+     *        Nor does it verify whether any column rule already exists at $toColumn, but will simply override any existing value.
      *        Use with caution.
      *
      * @param string $fromColumn Column name (e.g. A)
@@ -286,7 +286,7 @@ class AutoFilter
      *
      * @return AutoFilter
      */
-    public function shiftColumn($fromColumn = null, $toColumn = null)
+    public function shiftColumn($fromColumn, $toColumn)
     {
         $fromColumn = strtoupper($fromColumn);
         $toColumn = strtoupper($toColumn);
diff --git a/src/PhpSpreadsheet/Worksheet/AutoFilter/Column.php b/src/PhpSpreadsheet/Worksheet/AutoFilter/Column.php
index b5c0fbaa..305d70bf 100644
--- a/src/PhpSpreadsheet/Worksheet/AutoFilter/Column.php
+++ b/src/PhpSpreadsheet/Worksheet/AutoFilter/Column.php
@@ -194,7 +194,7 @@ class Column
      *
      * @return Column
      */
-    public function setFilterType($pFilterType = self::AUTOFILTER_FILTERTYPE_FILTER)
+    public function setFilterType($pFilterType)
     {
         if (!in_array($pFilterType, self::$filterTypes)) {
             throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid filter type for column AutoFilter.');
@@ -224,7 +224,7 @@ class Column
      *
      * @return Column
      */
-    public function setJoin($pJoin = self::AUTOFILTER_COLUMN_JOIN_OR)
+    public function setJoin($pJoin)
     {
         // Lowercase And/Or
         $pJoin = strtolower($pJoin);
@@ -240,15 +240,15 @@ class Column
     /**
      * Set AutoFilter Attributes.
      *
-     * @param string[] $pAttributes
+     * @param string[] $attributes
      *
      * @throws \PhpOffice\PhpSpreadsheet\Exception
      *
      * @return Column
      */
-    public function setAttributes($pAttributes = [])
+    public function setAttributes(array $attributes)
     {
-        $this->attributes = $pAttributes;
+        $this->attributes = $attributes;
 
         return $this;
     }
@@ -273,7 +273,7 @@ class Column
     /**
      * Get AutoFilter Column Attributes.
      *
-     * @return string
+     * @return string[]
      */
     public function getAttributes()
     {
@@ -340,16 +340,15 @@ class Column
      * Add a new AutoFilter Column Rule to the ruleset.
      *
      * @param Column\Rule $pRule
-     * @param bool $returnRule Flag indicating whether the rule object or the column object should be returned
      *
-     * @return Column|Column\Rule
+     * @return Column
      */
-    public function addRule(Column\Rule $pRule, $returnRule = true)
+    public function addRule(Column\Rule $pRule)
     {
         $pRule->setParent($this);
         $this->ruleset[] = $pRule;
 
-        return ($returnRule) ? $pRule : $this;
+        return $this;
     }
 
     /**
diff --git a/src/PhpSpreadsheet/Worksheet/AutoFilter/Column/Rule.php b/src/PhpSpreadsheet/Worksheet/AutoFilter/Column/Rule.php
index f9daee1e..bdf6fd52 100644
--- a/src/PhpSpreadsheet/Worksheet/AutoFilter/Column/Rule.php
+++ b/src/PhpSpreadsheet/Worksheet/AutoFilter/Column/Rule.php
@@ -277,13 +277,13 @@ class Rule
     /**
      * Set AutoFilter Rule Type.
      *
-     * @param string $pRuleType
+     * @param string $pRuleType see self::AUTOFILTER_RULETYPE_*
      *
      * @throws \PhpOffice\PhpSpreadsheet\Exception
      *
      * @return Rule
      */
-    public function setRuleType($pRuleType = self::AUTOFILTER_RULETYPE_FILTER)
+    public function setRuleType($pRuleType)
     {
         if (!in_array($pRuleType, self::$ruleTypes)) {
             throw new \PhpOffice\PhpSpreadsheet\Exception('Invalid rule type for column AutoFilter Rule.');
@@ -313,7 +313,7 @@ class Rule
      *
      * @return Rule
      */
-    public function setValue($pValue = '')
+    public function setValue($pValue)
     {
         if (is_array($pValue)) {
             $grouping = -1;
@@ -351,13 +351,13 @@ class Rule
     /**
      * Set AutoFilter Rule Operator.
      *
-     * @param string $pOperator
+     * @param string $pOperator see self::AUTOFILTER_COLUMN_RULE_*
      *
      * @throws \PhpOffice\PhpSpreadsheet\Exception
      *
      * @return Rule
      */
-    public function setOperator($pOperator = self::AUTOFILTER_COLUMN_RULE_EQUAL)
+    public function setOperator($pOperator)
     {
         if (empty($pOperator)) {
             $pOperator = self::AUTOFILTER_COLUMN_RULE_EQUAL;
@@ -390,7 +390,7 @@ class Rule
      *
      * @return Rule
      */
-    public function setGrouping($pGrouping = null)
+    public function setGrouping($pGrouping)
     {
         if (($pGrouping !== null) &&
             (!in_array($pGrouping, self::$dateTimeGroups)) &&
@@ -406,7 +406,7 @@ class Rule
     /**
      * Set AutoFilter Rule.
      *
-     * @param string $pOperator
+     * @param string $pOperator see self::AUTOFILTER_COLUMN_RULE_*
      * @param string|string[] $pValue
      * @param string $pGrouping
      *
@@ -414,7 +414,7 @@ class Rule
      *
      * @return Rule
      */
-    public function setRule($pOperator = self::AUTOFILTER_COLUMN_RULE_EQUAL, $pValue = '', $pGrouping = null)
+    public function setRule($pOperator, $pValue, $pGrouping = null)
     {
         $this->setOperator($pOperator);
         $this->setValue($pValue);
diff --git a/src/PhpSpreadsheet/Worksheet/BaseDrawing.php b/src/PhpSpreadsheet/Worksheet/BaseDrawing.php
index dbf75f24..9f975309 100644
--- a/src/PhpSpreadsheet/Worksheet/BaseDrawing.php
+++ b/src/PhpSpreadsheet/Worksheet/BaseDrawing.php
@@ -166,7 +166,7 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return BaseDrawing
      */
-    public function setName($pValue = '')
+    public function setName($pValue)
     {
         $this->name = $pValue;
 
@@ -186,13 +186,13 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
     /**
      * Set Description.
      *
-     * @param string $pValue
+     * @param string $description
      *
      * @return BaseDrawing
      */
-    public function setDescription($pValue = '')
+    public function setDescription($description)
     {
-        $this->description = $pValue;
+        $this->description = $description;
 
         return $this;
     }
@@ -260,11 +260,11 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
     /**
      * Set Coordinates.
      *
-     * @param string $pValue
+     * @param string $pValue eg: 'A1'
      *
      * @return BaseDrawing
      */
-    public function setCoordinates($pValue = 'A1')
+    public function setCoordinates($pValue)
     {
         $this->coordinates = $pValue;
 
@@ -288,7 +288,7 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return BaseDrawing
      */
-    public function setOffsetX($pValue = 0)
+    public function setOffsetX($pValue)
     {
         $this->offsetX = $pValue;
 
@@ -312,7 +312,7 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return BaseDrawing
      */
-    public function setOffsetY($pValue = 0)
+    public function setOffsetY($pValue)
     {
         $this->offsetY = $pValue;
 
@@ -336,7 +336,7 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return BaseDrawing
      */
-    public function setWidth($pValue = 0)
+    public function setWidth($pValue)
     {
         // Resize proportional?
         if ($this->resizeProportional && $pValue != 0) {
@@ -367,7 +367,7 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return BaseDrawing
      */
-    public function setHeight($pValue = 0)
+    public function setHeight($pValue)
     {
         // Resize proportional?
         if ($this->resizeProportional && $pValue != 0) {
@@ -396,7 +396,7 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return BaseDrawing
      */
-    public function setWidthAndHeight($width = 0, $height = 0)
+    public function setWidthAndHeight($width, $height)
     {
         $xratio = $width / ($this->width != 0 ? $this->width : 1);
         $yratio = $height / ($this->height != 0 ? $this->height : 1);
@@ -433,7 +433,7 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return BaseDrawing
      */
-    public function setResizeProportional($pValue = true)
+    public function setResizeProportional($pValue)
     {
         $this->resizeProportional = $pValue;
 
@@ -457,7 +457,7 @@ class BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return BaseDrawing
      */
-    public function setRotation($pValue = 0)
+    public function setRotation($pValue)
     {
         $this->rotation = $pValue;
 
diff --git a/src/PhpSpreadsheet/Worksheet/CellIterator.php b/src/PhpSpreadsheet/Worksheet/CellIterator.php
index 9dced6b3..cc3b10ea 100644
--- a/src/PhpSpreadsheet/Worksheet/CellIterator.php
+++ b/src/PhpSpreadsheet/Worksheet/CellIterator.php
@@ -79,7 +79,7 @@ abstract class CellIterator
      *
      * @throws \PhpOffice\PhpSpreadsheet\Exception
      */
-    public function setIterateOnlyExistingCells($value = true)
+    public function setIterateOnlyExistingCells($value)
     {
         $this->onlyExistingCells = (bool) $value;
 
diff --git a/src/PhpSpreadsheet/Worksheet/ColumnDimension.php b/src/PhpSpreadsheet/Worksheet/ColumnDimension.php
index 7aa214de..b3b4b312 100644
--- a/src/PhpSpreadsheet/Worksheet/ColumnDimension.php
+++ b/src/PhpSpreadsheet/Worksheet/ColumnDimension.php
@@ -104,7 +104,7 @@ class ColumnDimension extends Dimension
      *
      * @return ColumnDimension
      */
-    public function setWidth($pValue = -1)
+    public function setWidth($pValue)
     {
         $this->width = $pValue;
 
@@ -128,7 +128,7 @@ class ColumnDimension extends Dimension
      *
      * @return ColumnDimension
      */
-    public function setAutoSize($pValue = false)
+    public function setAutoSize($pValue)
     {
         $this->autoSize = $pValue;
 
diff --git a/src/PhpSpreadsheet/Worksheet/Dimension.php b/src/PhpSpreadsheet/Worksheet/Dimension.php
index 41493985..2ff18512 100644
--- a/src/PhpSpreadsheet/Worksheet/Dimension.php
+++ b/src/PhpSpreadsheet/Worksheet/Dimension.php
@@ -82,7 +82,7 @@ abstract class Dimension
      *
      * @return Dimension
      */
-    public function setVisible($pValue = true)
+    public function setVisible($pValue)
     {
         $this->visible = $pValue;
 
@@ -138,7 +138,7 @@ abstract class Dimension
      *
      * @return Dimension
      */
-    public function setCollapsed($pValue = true)
+    public function setCollapsed($pValue)
     {
         $this->collapsed = $pValue;
 
@@ -162,7 +162,7 @@ abstract class Dimension
      *
      * @return Dimension
      */
-    public function setXfIndex($pValue = 0)
+    public function setXfIndex($pValue)
     {
         $this->xfIndex = $pValue;
 
diff --git a/src/PhpSpreadsheet/Worksheet/Drawing.php b/src/PhpSpreadsheet/Worksheet/Drawing.php
index 26d40f9e..8154e501 100644
--- a/src/PhpSpreadsheet/Worksheet/Drawing.php
+++ b/src/PhpSpreadsheet/Worksheet/Drawing.php
@@ -100,7 +100,7 @@ class Drawing extends BaseDrawing implements \PhpOffice\PhpSpreadsheet\IComparab
      *
      * @return Drawing
      */
-    public function setPath($pValue = '', $pVerifyFile = true)
+    public function setPath($pValue, $pVerifyFile = true)
     {
         if ($pVerifyFile) {
             if (file_exists($pValue)) {
diff --git a/src/PhpSpreadsheet/Worksheet/Drawing/Shadow.php b/src/PhpSpreadsheet/Worksheet/Drawing/Shadow.php
index 644fe708..54f23a83 100644
--- a/src/PhpSpreadsheet/Worksheet/Drawing/Shadow.php
+++ b/src/PhpSpreadsheet/Worksheet/Drawing/Shadow.php
@@ -121,7 +121,7 @@ class Shadow implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Shadow
      */
-    public function setVisible($pValue = false)
+    public function setVisible($pValue)
     {
         $this->visible = $pValue;
 
@@ -145,7 +145,7 @@ class Shadow implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Shadow
      */
-    public function setBlurRadius($pValue = 6)
+    public function setBlurRadius($pValue)
     {
         $this->blurRadius = $pValue;
 
@@ -169,7 +169,7 @@ class Shadow implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Shadow
      */
-    public function setDistance($pValue = 2)
+    public function setDistance($pValue)
     {
         $this->distance = $pValue;
 
@@ -193,7 +193,7 @@ class Shadow implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Shadow
      */
-    public function setDirection($pValue = 0)
+    public function setDirection($pValue)
     {
         $this->direction = $pValue;
 
@@ -217,7 +217,7 @@ class Shadow implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Shadow
      */
-    public function setAlignment($pValue = 0)
+    public function setAlignment($pValue)
     {
         $this->alignment = $pValue;
 
@@ -267,7 +267,7 @@ class Shadow implements \PhpOffice\PhpSpreadsheet\IComparable
      *
      * @return Shadow
      */
-    public function setAlpha($pValue = 0)
+    public function setAlpha($pValue)
     {
         $this->alpha = $pValue;
 
diff --git a/src/PhpSpreadsheet/Worksheet/HeaderFooter.php b/src/PhpSpreadsheet/Worksheet/HeaderFooter.php
index a8f5cf65..d7a52caa 100644
--- a/src/PhpSpreadsheet/Worksheet/HeaderFooter.php
+++ b/src/PhpSpreadsheet/Worksheet/HeaderFooter.php
@@ -339,7 +339,7 @@ class HeaderFooter
      *
      * @return HeaderFooter
      */
-    public function setDifferentOddEven($pValue = false)
+    public function setDifferentOddEven($pValue)
     {
         $this->differentOddEven = $pValue;
 
@@ -363,7 +363,7 @@ class HeaderFooter
      *
      * @return HeaderFooter
      */
-    public function setDifferentFirst($pValue = false)
+    public function setDifferentFirst($pValue)
     {
         $this->differentFirst = $pValue;
 
@@ -387,7 +387,7 @@ class HeaderFooter
      *
      * @return HeaderFooter
      */
-    public function setScaleWithDocument($pValue = true)
+    public function setScaleWithDocument($pValue)
     {
         $this->scaleWithDocument = $pValue;
 
@@ -411,7 +411,7 @@ class HeaderFooter
      *
      * @return HeaderFooter
      */
-    public function setAlignWithMargins($pValue = true)
+    public function setAlignWithMargins($pValue)
     {
         $this->alignWithMargins = $pValue;
 
diff --git a/src/PhpSpreadsheet/Worksheet/HeaderFooterDrawing.php b/src/PhpSpreadsheet/Worksheet/HeaderFooterDrawing.php
index 57a888b2..6db76ff5 100644
--- a/src/PhpSpreadsheet/Worksheet/HeaderFooterDrawing.php
+++ b/src/PhpSpreadsheet/Worksheet/HeaderFooterDrawing.php
@@ -107,7 +107,7 @@ class HeaderFooterDrawing extends Drawing implements \PhpOffice\PhpSpreadsheet\I
      *
      * @return HeaderFooterDrawing
      */
-    public function setName($pValue = '')
+    public function setName($pValue)
     {
         $this->name = $pValue;
 
@@ -131,7 +131,7 @@ class HeaderFooterDrawing extends Drawing implements \PhpOffice\PhpSpreadsheet\I
      *
      * @return HeaderFooterDrawing
      */
-    public function setOffsetX($pValue = 0)
+    public function setOffsetX($pValue)
     {
         $this->offsetX = $pValue;
 
@@ -155,7 +155,7 @@ class HeaderFooterDrawing extends Drawing implements \PhpOffice\PhpSpreadsheet\I
      *
      * @return HeaderFooterDrawing
      */
-    public function setOffsetY($pValue = 0)
+    public function setOffsetY($pValue)
     {
         $this->offsetY = $pValue;
 
@@ -179,7 +179,7 @@ class HeaderFooterDrawing extends Drawing implements \PhpOffice\PhpSpreadsheet\I
      *
      * @return HeaderFooterDrawing
      */
-    public function setWidth($pValue = 0)
+    public function setWidth($pValue)
     {
         // Resize proportional?
         if ($this->resizeProportional && $pValue != 0) {
@@ -210,7 +210,7 @@ class HeaderFooterDrawing extends Drawing implements \PhpOffice\PhpSpreadsheet\I
      *
      * @return HeaderFooterDrawing
      */
-    public function setHeight($pValue = 0)
+    public function setHeight($pValue)
     {
         // Resize proportional?
         if ($this->resizeProportional && $pValue != 0) {
@@ -239,7 +239,7 @@ class HeaderFooterDrawing extends Drawing implements \PhpOffice\PhpSpreadsheet\I
      *
      * @return HeaderFooterDrawing
      */
-    public function setWidthAndHeight($width = 0, $height = 0)
+    public function setWidthAndHeight($width, $height)
     {
         $xratio = $width / $this->width;
         $yratio = $height / $this->height;
@@ -273,7 +273,7 @@ class HeaderFooterDrawing extends Drawing implements \PhpOffice\PhpSpreadsheet\I
      *
      * @return HeaderFooterDrawing
      */
-    public function setResizeProportional($pValue = true)
+    public function setResizeProportional($pValue)
     {
         $this->resizeProportional = $pValue;
 
@@ -322,7 +322,7 @@ class HeaderFooterDrawing extends Drawing implements \PhpOffice\PhpSpreadsheet\I
      *
      * @return HeaderFooterDrawing
      */
-    public function setPath($pValue = '', $pVerifyFile = true)
+    public function setPath($pValue, $pVerifyFile = true)
     {
         if ($pVerifyFile) {
             if (file_exists($pValue)) {
diff --git a/src/PhpSpreadsheet/Worksheet/MemoryDrawing.php b/src/PhpSpreadsheet/Worksheet/MemoryDrawing.php
index 4011aa59..b543b8d0 100644
--- a/src/PhpSpreadsheet/Worksheet/MemoryDrawing.php
+++ b/src/PhpSpreadsheet/Worksheet/MemoryDrawing.php
@@ -94,11 +94,11 @@ class MemoryDrawing extends BaseDrawing implements \PhpOffice\PhpSpreadsheet\ICo
     /**
      * Set image resource.
      *
-     * @param $value resource
+     * @param resource $value
      *
      * @return MemoryDrawing
      */
-    public function setImageResource($value = null)
+    public function setImageResource($value)
     {
         $this->imageResource = $value;
 
@@ -124,11 +124,11 @@ class MemoryDrawing extends BaseDrawing implements \PhpOffice\PhpSpreadsheet\ICo
     /**
      * Set rendering function.
      *
-     * @param string $value
+     * @param string $value see self::RENDERING_*
      *
      * @return MemoryDrawing
      */
-    public function setRenderingFunction($value = self::RENDERING_DEFAULT)
+    public function setRenderingFunction($value)
     {
         $this->renderingFunction = $value;
 
@@ -148,11 +148,11 @@ class MemoryDrawing extends BaseDrawing implements \PhpOffice\PhpSpreadsheet\ICo
     /**
      * Set mime type.
      *
-     * @param string $value
+     * @param string $value see self::MIMETYPE_*
      *
      * @return MemoryDrawing
      */
-    public function setMimeType($value = self::MIMETYPE_DEFAULT)
+    public function setMimeType($value)
     {
         $this->mimeType = $value;
 
diff --git a/src/PhpSpreadsheet/Worksheet/PageSetup.php b/src/PhpSpreadsheet/Worksheet/PageSetup.php
index 41a1a22e..8e40ca1d 100644
--- a/src/PhpSpreadsheet/Worksheet/PageSetup.php
+++ b/src/PhpSpreadsheet/Worksheet/PageSetup.php
@@ -288,11 +288,11 @@ class PageSetup
     /**
      * Set Paper Size.
      *
-     * @param int $pValue
+     * @param int $pValue see self::PAPERSIZE_*
      *
      * @return PageSetup
      */
-    public function setPaperSize($pValue = self::PAPERSIZE_LETTER)
+    public function setPaperSize($pValue)
     {
         $this->paperSize = $pValue;
 
@@ -312,11 +312,11 @@ class PageSetup
     /**
      * Set Orientation.
      *
-     * @param string $pValue
+     * @param string $pValue see self::ORIENTATION_*
      *
      * @return PageSetup
      */
-    public function setOrientation($pValue = self::ORIENTATION_DEFAULT)
+    public function setOrientation($pValue)
     {
         $this->orientation = $pValue;
 
@@ -339,14 +339,14 @@ class PageSetup
      * Print scaling. Valid values range from 10 to 400
      * This setting is overridden when fitToWidth and/or fitToHeight are in use
      *
-     * @param int? $pValue
+     * @param int|null $pValue
      * @param bool $pUpdate Update fitToPage so scaling applies rather than fitToHeight / fitToWidth
      *
      * @throws \PhpOffice\PhpSpreadsheet\Exception
      *
      * @return PageSetup
      */
-    public function setScale($pValue = 100, $pUpdate = true)
+    public function setScale($pValue, $pUpdate = true)
     {
         // Microsoft Office Excel 2007 only allows setting a scale between 10 and 400 via the user interface,
         // but it is apparently still able to handle any scale >= 0, where 0 results in 100
@@ -379,7 +379,7 @@ class PageSetup
      *
      * @return PageSetup
      */
-    public function setFitToPage($pValue = true)
+    public function setFitToPage($pValue)
     {
         $this->fitToPage = $pValue;
 
@@ -399,12 +399,12 @@ class PageSetup
     /**
      * Set Fit To Height.
      *
-     * @param int? $pValue
+     * @param int|null $pValue
      * @param bool $pUpdate Update fitToPage so it applies rather than scaling
      *
      * @return PageSetup
      */
-    public function setFitToHeight($pValue = 1, $pUpdate = true)
+    public function setFitToHeight($pValue, $pUpdate = true)
     {
         $this->fitToHeight = $pValue;
         if ($pUpdate) {
@@ -427,12 +427,12 @@ class PageSetup
     /**
      * Set Fit To Width.
      *
-     * @param int? $pValue
+     * @param int|null $pValue
      * @param bool $pUpdate Update fitToPage so it applies rather than scaling
      *
      * @return PageSetup
      */
-    public function setFitToWidth($pValue = 1, $pUpdate = true)
+    public function setFitToWidth($pValue, $pUpdate = true)
     {
         $this->fitToWidth = $pValue;
         if ($pUpdate) {
@@ -475,11 +475,9 @@ class PageSetup
      *
      * @return PageSetup
      */
-    public function setColumnsToRepeatAtLeft($pValue = null)
+    public function setColumnsToRepeatAtLeft(array $pValue)
     {
-        if (is_array($pValue)) {
-            $this->columnsToRepeatAtLeft = $pValue;
-        }
+        $this->columnsToRepeatAtLeft = $pValue;
 
         return $this;
     }
@@ -487,12 +485,12 @@ class PageSetup
     /**
      * Set Columns to repeat at left by start and end.
      *
-     * @param string $pStart
-     * @param string $pEnd
+     * @param string $pStart eg: 'A'
+     * @param string $pEnd eg: 'B'
      *
      * @return PageSetup
      */
-    public function setColumnsToRepeatAtLeftByStartAndEnd($pStart = 'A', $pEnd = 'A')
+    public function setColumnsToRepeatAtLeftByStartAndEnd($pStart, $pEnd)
     {
         $this->columnsToRepeatAtLeft = [$pStart, $pEnd];
 
@@ -532,11 +530,9 @@ class PageSetup
      *
      * @return PageSetup
      */
-    public function setRowsToRepeatAtTop($pValue = null)
+    public function setRowsToRepeatAtTop(array $pValue)
     {
-        if (is_array($pValue)) {
-            $this->rowsToRepeatAtTop = $pValue;
-        }
+        $this->rowsToRepeatAtTop = $pValue;
 
         return $this;
     }
@@ -544,12 +540,12 @@ class PageSetup
     /**
      * Set Rows to repeat at top by start and end.
      *
-     * @param int $pStart
-     * @param int $pEnd
+     * @param int $pStart eg: 1
+     * @param int $pEnd eg: 1
      *
      * @return PageSetup
      */
-    public function setRowsToRepeatAtTopByStartAndEnd($pStart = 1, $pEnd = 1)
+    public function setRowsToRepeatAtTopByStartAndEnd($pStart, $pEnd)
     {
         $this->rowsToRepeatAtTop = [$pStart, $pEnd];
 
@@ -573,7 +569,7 @@ class PageSetup
      *
      * @return PageSetup
      */
-    public function setHorizontalCentered($value = false)
+    public function setHorizontalCentered($value)
     {
         $this->horizontalCentered = $value;
 
@@ -597,7 +593,7 @@ class PageSetup
      *
      * @return PageSetup
      */
-    public function setVerticalCentered($value = false)
+    public function setVerticalCentered($value)
     {
         $this->verticalCentered = $value;
 
@@ -839,7 +835,7 @@ class PageSetup
      *
      * @return PageSetup
      */
-    public function setFirstPageNumber($value = null)
+    public function setFirstPageNumber($value)
     {
         $this->firstPageNumber = $value;
 
diff --git a/src/PhpSpreadsheet/Worksheet/Protection.php b/src/PhpSpreadsheet/Worksheet/Protection.php
index cda264ee..ddb2dac3 100644
--- a/src/PhpSpreadsheet/Worksheet/Protection.php
+++ b/src/PhpSpreadsheet/Worksheet/Protection.php
@@ -194,7 +194,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setSheet($pValue = false)
+    public function setSheet($pValue)
     {
         $this->sheet = $pValue;
 
@@ -218,7 +218,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setObjects($pValue = false)
+    public function setObjects($pValue)
     {
         $this->objects = $pValue;
 
@@ -242,7 +242,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setScenarios($pValue = false)
+    public function setScenarios($pValue)
     {
         $this->scenarios = $pValue;
 
@@ -266,7 +266,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setFormatCells($pValue = false)
+    public function setFormatCells($pValue)
     {
         $this->formatCells = $pValue;
 
@@ -290,7 +290,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setFormatColumns($pValue = false)
+    public function setFormatColumns($pValue)
     {
         $this->formatColumns = $pValue;
 
@@ -314,7 +314,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setFormatRows($pValue = false)
+    public function setFormatRows($pValue)
     {
         $this->formatRows = $pValue;
 
@@ -338,7 +338,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setInsertColumns($pValue = false)
+    public function setInsertColumns($pValue)
     {
         $this->insertColumns = $pValue;
 
@@ -362,7 +362,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setInsertRows($pValue = false)
+    public function setInsertRows($pValue)
     {
         $this->insertRows = $pValue;
 
@@ -386,7 +386,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setInsertHyperlinks($pValue = false)
+    public function setInsertHyperlinks($pValue)
     {
         $this->insertHyperlinks = $pValue;
 
@@ -410,7 +410,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setDeleteColumns($pValue = false)
+    public function setDeleteColumns($pValue)
     {
         $this->deleteColumns = $pValue;
 
@@ -434,7 +434,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setDeleteRows($pValue = false)
+    public function setDeleteRows($pValue)
     {
         $this->deleteRows = $pValue;
 
@@ -458,7 +458,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setSelectLockedCells($pValue = false)
+    public function setSelectLockedCells($pValue)
     {
         $this->selectLockedCells = $pValue;
 
@@ -482,7 +482,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setSort($pValue = false)
+    public function setSort($pValue)
     {
         $this->sort = $pValue;
 
@@ -506,7 +506,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setAutoFilter($pValue = false)
+    public function setAutoFilter($pValue)
     {
         $this->autoFilter = $pValue;
 
@@ -530,7 +530,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setPivotTables($pValue = false)
+    public function setPivotTables($pValue)
     {
         $this->pivotTables = $pValue;
 
@@ -554,7 +554,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setSelectUnlockedCells($pValue = false)
+    public function setSelectUnlockedCells($pValue)
     {
         $this->selectUnlockedCells = $pValue;
 
@@ -579,7 +579,7 @@ class Protection
      *
      * @return Protection
      */
-    public function setPassword($pValue = '', $pAlreadyHashed = false)
+    public function setPassword($pValue, $pAlreadyHashed = false)
     {
         if (!$pAlreadyHashed) {
             $pValue = \PhpOffice\PhpSpreadsheet\Shared\PasswordHasher::hashPassword($pValue);
diff --git a/src/PhpSpreadsheet/Worksheet/RowDimension.php b/src/PhpSpreadsheet/Worksheet/RowDimension.php
index d48a97bd..58ba4185 100644
--- a/src/PhpSpreadsheet/Worksheet/RowDimension.php
+++ b/src/PhpSpreadsheet/Worksheet/RowDimension.php
@@ -104,7 +104,7 @@ class RowDimension extends Dimension
      *
      * @return RowDimension
      */
-    public function setRowHeight($pValue = -1)
+    public function setRowHeight($pValue)
     {
         $this->height = $pValue;
 
@@ -128,7 +128,7 @@ class RowDimension extends Dimension
      *
      * @return RowDimension
      */
-    public function setZeroHeight($pValue = false)
+    public function setZeroHeight($pValue)
     {
         $this->zeroHeight = $pValue;
 
diff --git a/src/PhpSpreadsheet/Worksheet/SheetView.php b/src/PhpSpreadsheet/Worksheet/SheetView.php
index 64c60522..7ce233ce 100644
--- a/src/PhpSpreadsheet/Worksheet/SheetView.php
+++ b/src/PhpSpreadsheet/Worksheet/SheetView.php
@@ -92,7 +92,7 @@ class SheetView
      *
      * @return SheetView
      */
-    public function setZoomScale($pValue = 100)
+    public function setZoomScale($pValue)
     {
         // Microsoft Office Excel 2007 only allows setting a scale between 10 and 400 via the user interface,
         // but it is apparently still able to handle any scale >= 1
@@ -126,7 +126,7 @@ class SheetView
      *
      * @return SheetView
      */
-    public function setZoomScaleNormal($pValue = 100)
+    public function setZoomScaleNormal($pValue)
     {
         if (($pValue >= 1) || is_null($pValue)) {
             $this->zoomScaleNormal = $pValue;
@@ -161,7 +161,7 @@ class SheetView
      *
      * @return SheetView
      */
-    public function setView($pValue = null)
+    public function setView($pValue)
     {
         // MS Excel 2007 allows setting the view to 'normal', 'pageLayout' or 'pageBreakPreview' via the user interface
         if ($pValue === null) {
diff --git a/src/PhpSpreadsheet/Writer/BaseWriter.php b/src/PhpSpreadsheet/Writer/BaseWriter.php
index 67d60017..eb6f2a18 100644
--- a/src/PhpSpreadsheet/Writer/BaseWriter.php
+++ b/src/PhpSpreadsheet/Writer/BaseWriter.php
@@ -48,14 +48,14 @@ abstract class BaseWriter implements IWriter
      *
      * @var bool
      */
-    protected $_useDiskCaching = false;
+    private $useDiskCaching = false;
 
     /**
      * Disk caching directory.
      *
      * @var string
      */
-    protected $_diskCachingDirectory = './';
+    private $diskCachingDirectory = './';
 
     /**
      * Write charts in workbook?
@@ -78,7 +78,7 @@ abstract class BaseWriter implements IWriter
      *
      * @return IWriter
      */
-    public function setIncludeCharts($pValue = false)
+    public function setIncludeCharts($pValue)
     {
         $this->includeCharts = (bool) $pValue;
 
@@ -109,7 +109,7 @@ abstract class BaseWriter implements IWriter
      *
      * @return IWriter
      */
-    public function setPreCalculateFormulas($pValue = true)
+    public function setPreCalculateFormulas($pValue)
     {
         $this->preCalculateFormulas = (bool) $pValue;
 
@@ -123,7 +123,7 @@ abstract class BaseWriter implements IWriter
      */
     public function getUseDiskCaching()
     {
-        return $this->_useDiskCaching;
+        return $this->useDiskCaching;
     }
 
     /**
@@ -136,13 +136,13 @@ abstract class BaseWriter implements IWriter
      *
      * @return IWriter
      */
-    public function setUseDiskCaching($pValue = false, $pDirectory = null)
+    public function setUseDiskCaching($pValue, $pDirectory = null)
     {
-        $this->_useDiskCaching = $pValue;
+        $this->useDiskCaching = $pValue;
 
         if ($pDirectory !== null) {
             if (is_dir($pDirectory)) {
-                $this->_diskCachingDirectory = $pDirectory;
+                $this->diskCachingDirectory = $pDirectory;
             } else {
                 throw new Exception("Directory does not exist: $pDirectory");
             }
@@ -158,6 +158,6 @@ abstract class BaseWriter implements IWriter
      */
     public function getDiskCachingDirectory()
     {
-        return $this->_diskCachingDirectory;
+        return $this->diskCachingDirectory;
     }
 }
diff --git a/src/PhpSpreadsheet/Writer/Csv.php b/src/PhpSpreadsheet/Writer/Csv.php
index 07afe03e..4ed6f89d 100644
--- a/src/PhpSpreadsheet/Writer/Csv.php
+++ b/src/PhpSpreadsheet/Writer/Csv.php
@@ -100,7 +100,7 @@ class Csv extends BaseWriter implements IWriter
      *
      * @throws Exception
      */
-    public function save($pFilename = null)
+    public function save($pFilename)
     {
         // Fetch sheet
         $sheet = $this->spreadsheet->getSheet($this->sheetIndex);
@@ -164,11 +164,11 @@ class Csv extends BaseWriter implements IWriter
     /**
      * Set delimiter.
      *
-     * @param string $pValue Delimiter, defaults to ,
+     * @param string $pValue Delimiter, defaults to ','
      *
      * @return CSV
      */
-    public function setDelimiter($pValue = ',')
+    public function setDelimiter($pValue)
     {
         $this->delimiter = $pValue;
 
@@ -192,7 +192,7 @@ class Csv extends BaseWriter implements IWriter
      *
      * @return CSV
      */
-    public function setEnclosure($pValue = '"')
+    public function setEnclosure($pValue)
     {
         if ($pValue == '') {
             $pValue = null;
@@ -219,7 +219,7 @@ class Csv extends BaseWriter implements IWriter
      *
      * @return CSV
      */
-    public function setLineEnding($pValue = PHP_EOL)
+    public function setLineEnding($pValue)
     {
         $this->lineEnding = $pValue;
 
@@ -243,7 +243,7 @@ class Csv extends BaseWriter implements IWriter
      *
      * @return CSV
      */
-    public function setUseBOM($pValue = false)
+    public function setUseBOM($pValue)
     {
         $this->useBOM = $pValue;
 
@@ -267,7 +267,7 @@ class Csv extends BaseWriter implements IWriter
      *
      * @return CSV
      */
-    public function setIncludeSeparatorLine($pValue = false)
+    public function setIncludeSeparatorLine($pValue)
     {
         $this->includeSeparatorLine = $pValue;
 
@@ -292,7 +292,7 @@ class Csv extends BaseWriter implements IWriter
      *
      * @return CSV
      */
-    public function setExcelCompatibility($pValue = false)
+    public function setExcelCompatibility($pValue)
     {
         $this->excelCompatibility = $pValue;
 
@@ -316,7 +316,7 @@ class Csv extends BaseWriter implements IWriter
      *
      * @return CSV
      */
-    public function setSheetIndex($pValue = 0)
+    public function setSheetIndex($pValue)
     {
         $this->sheetIndex = $pValue;
 
@@ -331,37 +331,33 @@ class Csv extends BaseWriter implements IWriter
      *
      * @throws Exception
      */
-    private function writeLine($pFileHandle = null, $pValues = null)
+    private function writeLine($pFileHandle, array $pValues)
     {
-        if (is_array($pValues)) {
-            // No leading delimiter
-            $writeDelimiter = false;
+        // No leading delimiter
+        $writeDelimiter = false;
 
-            // Build the line
-            $line = '';
+        // Build the line
+        $line = '';
 
-            foreach ($pValues as $element) {
-                // Escape enclosures
-                $element = str_replace($this->enclosure, $this->enclosure . $this->enclosure, $element);
+        foreach ($pValues as $element) {
+            // Escape enclosures
+            $element = str_replace($this->enclosure, $this->enclosure . $this->enclosure, $element);
 
-                // Add delimiter
-                if ($writeDelimiter) {
-                    $line .= $this->delimiter;
-                } else {
-                    $writeDelimiter = true;
-                }
-
-                // Add enclosed string
-                $line .= $this->enclosure . $element . $this->enclosure;
+            // Add delimiter
+            if ($writeDelimiter) {
+                $line .= $this->delimiter;
+            } else {
+                $writeDelimiter = true;
             }
 
-            // Add line ending
-            $line .= $this->lineEnding;
-
-            // Write to file
-            fwrite($pFileHandle, $line);
-        } else {
-            throw new Exception('Invalid data row passed to CSV writer.');
+            // Add enclosed string
+            $line .= $this->enclosure . $element . $this->enclosure;
         }
+
+        // Add line ending
+        $line .= $this->lineEnding;
+
+        // Write to file
+        fwrite($pFileHandle, $line);
     }
 }
diff --git a/src/PhpSpreadsheet/Writer/Html.php b/src/PhpSpreadsheet/Writer/Html.php
index 779113df..65d95a05 100644
--- a/src/PhpSpreadsheet/Writer/Html.php
+++ b/src/PhpSpreadsheet/Writer/Html.php
@@ -147,7 +147,7 @@ class Html extends BaseWriter implements IWriter
      *
      * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
      */
-    public function save($pFilename = null)
+    public function save($pFilename)
     {
         // garbage collect
         $this->spreadsheet->garbageCollect();
@@ -296,7 +296,7 @@ class Html extends BaseWriter implements IWriter
      *
      * @return HTML
      */
-    public function setSheetIndex($pValue = 0)
+    public function setSheetIndex($pValue)
     {
         $this->sheetIndex = $pValue;
 
@@ -320,7 +320,7 @@ class Html extends BaseWriter implements IWriter
      *
      * @return HTML
      */
-    public function setGenerateSheetNavigationBlock($pValue = true)
+    public function setGenerateSheetNavigationBlock($pValue)
     {
         $this->generateSheetNavigationBlock = (bool) $pValue;
 
@@ -1457,7 +1457,7 @@ class Html extends BaseWriter implements IWriter
      *
      * @return HTML
      */
-    public function setImagesRoot($pValue = '.')
+    public function setImagesRoot($pValue)
     {
         $this->imagesRoot = $pValue;
 
@@ -1481,7 +1481,7 @@ class Html extends BaseWriter implements IWriter
      *
      * @return HTML
      */
-    public function setEmbedImages($pValue = true)
+    public function setEmbedImages($pValue)
     {
         $this->embedImages = $pValue;
 
@@ -1505,7 +1505,7 @@ class Html extends BaseWriter implements IWriter
      *
      * @return HTML
      */
-    public function setUseInlineCss($pValue = false)
+    public function setUseInlineCss($pValue)
     {
         $this->useInlineCss = $pValue;
 
diff --git a/src/PhpSpreadsheet/Writer/IWriter.php b/src/PhpSpreadsheet/Writer/IWriter.php
index 4093a34b..c1443481 100644
--- a/src/PhpSpreadsheet/Writer/IWriter.php
+++ b/src/PhpSpreadsheet/Writer/IWriter.php
@@ -33,5 +33,5 @@ interface IWriter
      *
      * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
      */
-    public function save($pFilename = null);
+    public function save($pFilename);
 }
diff --git a/src/PhpSpreadsheet/Writer/Ods.php b/src/PhpSpreadsheet/Writer/Ods.php
index 1203f68f..4276fa6d 100644
--- a/src/PhpSpreadsheet/Writer/Ods.php
+++ b/src/PhpSpreadsheet/Writer/Ods.php
@@ -74,7 +74,7 @@ class Ods extends BaseWriter implements IWriter
      *
      * @return Ods\WriterPart|null
      */
-    public function getWriterPart($pPartName = '')
+    public function getWriterPart($pPartName)
     {
         if ($pPartName != '' && isset($this->writerParts[strtolower($pPartName)])) {
             return $this->writerParts[strtolower($pPartName)];
@@ -90,7 +90,7 @@ class Ods extends BaseWriter implements IWriter
      *
      * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
      */
-    public function save($pFilename = null)
+    public function save($pFilename)
     {
         if (!$this->spreadSheet) {
             throw new \PhpOffice\PhpSpreadsheet\Writer\Exception('PhpSpreadsheet object unassigned.');
diff --git a/src/PhpSpreadsheet/Writer/Pdf.php b/src/PhpSpreadsheet/Writer/Pdf.php
index 2bb20fc7..eeec2334 100644
--- a/src/PhpSpreadsheet/Writer/Pdf.php
+++ b/src/PhpSpreadsheet/Writer/Pdf.php
@@ -73,7 +73,7 @@ class Pdf implements IWriter
     /**
      * {@inheritdoc}
      */
-    public function save($pFilename = null)
+    public function save($pFilename)
     {
         $this->renderer->save($pFilename);
     }
diff --git a/src/PhpSpreadsheet/Writer/Pdf/Core.php b/src/PhpSpreadsheet/Writer/Pdf/Core.php
index 6e429817..084b514c 100644
--- a/src/PhpSpreadsheet/Writer/Pdf/Core.php
+++ b/src/PhpSpreadsheet/Writer/Pdf/Core.php
@@ -186,11 +186,11 @@ abstract class Core extends \PhpOffice\PhpSpreadsheet\Writer\Html
     /**
      * Set Paper Size.
      *
-     * @param string $pValue Paper size
+     * @param string $pValue Paper size see \PhpOffice\PhpSpreadsheet\Worksheet\PageSetup::PAPERSIZE_*
      *
      * @return self
      */
-    public function setPaperSize($pValue = \PhpOffice\PhpSpreadsheet\Worksheet\PageSetup::PAPERSIZE_LETTER)
+    public function setPaperSize($pValue)
     {
         $this->paperSize = $pValue;
 
@@ -210,11 +210,11 @@ abstract class Core extends \PhpOffice\PhpSpreadsheet\Writer\Html
     /**
      * Set Orientation.
      *
-     * @param string $pValue Page orientation
+     * @param string $pValue Page orientation see \PhpOffice\PhpSpreadsheet\Worksheet\PageSetup::ORIENTATION_*
      *
      * @return self
      */
-    public function setOrientation($pValue = \PhpOffice\PhpSpreadsheet\Worksheet\PageSetup::ORIENTATION_DEFAULT)
+    public function setOrientation($pValue)
     {
         $this->orientation = $pValue;
 
@@ -240,7 +240,7 @@ abstract class Core extends \PhpOffice\PhpSpreadsheet\Writer\Html
      *
      * @return self
      */
-    public function setTempDir($pValue = '')
+    public function setTempDir($pValue)
     {
         if (is_dir($pValue)) {
             $this->tempDir = $pValue;
@@ -258,7 +258,7 @@ abstract class Core extends \PhpOffice\PhpSpreadsheet\Writer\Html
      *
      * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
      */
-    protected function prepareForSave($pFilename = null)
+    protected function prepareForSave($pFilename)
     {
         //  garbage collect
         $this->spreadsheet->garbageCollect();
diff --git a/src/PhpSpreadsheet/Writer/Pdf/DomPDF.php b/src/PhpSpreadsheet/Writer/Pdf/DomPDF.php
index 2fa219c8..2ddba79e 100644
--- a/src/PhpSpreadsheet/Writer/Pdf/DomPDF.php
+++ b/src/PhpSpreadsheet/Writer/Pdf/DomPDF.php
@@ -33,7 +33,7 @@ class DomPDF extends Core implements \PhpOffice\PhpSpreadsheet\Writer\IWriter
      *
      * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
      */
-    public function save($pFilename = null)
+    public function save($pFilename)
     {
         $fileHandle = parent::prepareForSave($pFilename);
 
diff --git a/src/PhpSpreadsheet/Writer/Pdf/MPDF.php b/src/PhpSpreadsheet/Writer/Pdf/MPDF.php
index 14feb1ff..06cb83e1 100644
--- a/src/PhpSpreadsheet/Writer/Pdf/MPDF.php
+++ b/src/PhpSpreadsheet/Writer/Pdf/MPDF.php
@@ -34,7 +34,7 @@ class MPDF extends Core implements \PhpOffice\PhpSpreadsheet\Writer\IWriter
      * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
      * @throws \PhpOffice\PhpSpreadsheet\Exception
      */
-    public function save($pFilename = null)
+    public function save($pFilename)
     {
         $fileHandle = parent::prepareForSave($pFilename);
 
diff --git a/src/PhpSpreadsheet/Writer/Pdf/TcPDF.php b/src/PhpSpreadsheet/Writer/Pdf/TcPDF.php
index 678a5591..858ff27e 100644
--- a/src/PhpSpreadsheet/Writer/Pdf/TcPDF.php
+++ b/src/PhpSpreadsheet/Writer/Pdf/TcPDF.php
@@ -33,7 +33,7 @@ class TcPDF extends Core implements \PhpOffice\PhpSpreadsheet\Writer\IWriter
      *
      * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
      */
-    public function save($pFilename = null)
+    public function save($pFilename)
     {
         $fileHandle = parent::prepareForSave($pFilename);
 
diff --git a/src/PhpSpreadsheet/Writer/Xls.php b/src/PhpSpreadsheet/Writer/Xls.php
index 2e228ad2..30698647 100644
--- a/src/PhpSpreadsheet/Writer/Xls.php
+++ b/src/PhpSpreadsheet/Writer/Xls.php
@@ -108,7 +108,7 @@ class Xls extends BaseWriter implements IWriter
      *
      * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
      */
-    public function save($pFilename = null)
+    public function save($pFilename)
     {
         // garbage collect
         $this->spreadsheet->garbageCollect();
diff --git a/src/PhpSpreadsheet/Writer/Xls/Workbook.php b/src/PhpSpreadsheet/Writer/Xls/Workbook.php
index 38ac7b30..2f2056e1 100644
--- a/src/PhpSpreadsheet/Writer/Xls/Workbook.php
+++ b/src/PhpSpreadsheet/Writer/Xls/Workbook.php
@@ -422,7 +422,7 @@ class Workbook extends BIFFwriter
      *
      * @return string Binary data for workbook stream
      */
-    public function writeWorkbook($pWorksheetSizes = null)
+    public function writeWorkbook(array $pWorksheetSizes)
     {
         $this->worksheetSizes = $pWorksheetSizes;
 
diff --git a/src/PhpSpreadsheet/Writer/Xls/Worksheet.php b/src/PhpSpreadsheet/Writer/Xls/Worksheet.php
index 006d1b22..464df8c3 100644
--- a/src/PhpSpreadsheet/Writer/Xls/Worksheet.php
+++ b/src/PhpSpreadsheet/Writer/Xls/Worksheet.php
@@ -539,7 +539,7 @@ class Worksheet extends BIFFwriter
      *
      * @return string Binary data
      */
-    private function writeBIFF8CellRangeAddressFixed($range = 'A1')
+    private function writeBIFF8CellRangeAddressFixed($range)
     {
         $explodes = explode(':', $range);
 
diff --git a/src/PhpSpreadsheet/Writer/Xlsx.php b/src/PhpSpreadsheet/Writer/Xlsx.php
index ff5f808f..0885f927 100644
--- a/src/PhpSpreadsheet/Writer/Xlsx.php
+++ b/src/PhpSpreadsheet/Writer/Xlsx.php
@@ -156,7 +156,7 @@ class Xlsx extends BaseWriter implements IWriter
      *
      * @return \PhpOffice\PhpSpreadsheet\Writer\Xlsx\WriterPart
      */
-    public function getWriterPart($pPartName = '')
+    public function getWriterPart($pPartName)
     {
         if ($pPartName != '' && isset($this->writerParts[strtolower($pPartName)])) {
             return $this->writerParts[strtolower($pPartName)];
@@ -172,7 +172,7 @@ class Xlsx extends BaseWriter implements IWriter
      *
      * @throws \PhpOffice\PhpSpreadsheet\Writer\Exception
      */
-    public function save($pFilename = null)
+    public function save($pFilename)
     {
         if ($this->spreadSheet !== null) {
             // garbage collect
@@ -515,7 +515,7 @@ class Xlsx extends BaseWriter implements IWriter
      *
      * @return Xlsx
      */
-    public function setOffice2003Compatibility($pValue = false)
+    public function setOffice2003Compatibility($pValue)
     {
         $this->office2003compatibility = $pValue;
 
diff --git a/src/PhpSpreadsheet/Writer/Xlsx/ContentTypes.php b/src/PhpSpreadsheet/Writer/Xlsx/ContentTypes.php
index ca6211f8..a600d39f 100644
--- a/src/PhpSpreadsheet/Writer/Xlsx/ContentTypes.php
+++ b/src/PhpSpreadsheet/Writer/Xlsx/ContentTypes.php
@@ -165,8 +165,8 @@ class ContentTypes extends WriterPart
         }
         $sheetCount = $spreadsheet->getSheetCount();
         for ($i = 0; $i < $sheetCount; ++$i) {
-            if (count($spreadsheet->getSheet()->getHeaderFooter()->getImages()) > 0) {
-                foreach ($spreadsheet->getSheet()->getHeaderFooter()->getImages() as $image) {
+            if (count($spreadsheet->getSheet($i)->getHeaderFooter()->getImages()) > 0) {
+                foreach ($spreadsheet->getSheet($i)->getHeaderFooter()->getImages() as $image) {
                     if (!isset($aMediaContentTypes[strtolower($image->getExtension())])) {
                         $aMediaContentTypes[strtolower($image->getExtension())] = $this->getImageMimeType($image->getPath());
 
@@ -191,7 +191,7 @@ class ContentTypes extends WriterPart
      *
      * @return string Mime Type
      */
-    private function getImageMimeType($pFile = '')
+    private function getImageMimeType($pFile)
     {
         if (\PhpOffice\PhpSpreadsheet\Shared\File::fileExists($pFile)) {
             $image = getimagesize($pFile);
diff --git a/src/PhpSpreadsheet/Writer/Xlsx/StringTable.php b/src/PhpSpreadsheet/Writer/Xlsx/StringTable.php
index 7a03dc66..195572f3 100644
--- a/src/PhpSpreadsheet/Writer/Xlsx/StringTable.php
+++ b/src/PhpSpreadsheet/Writer/Xlsx/StringTable.php
@@ -85,7 +85,7 @@ class StringTable extends WriterPart
      *
      * @return string XML Output
      */
-    public function writeStringTable($pStringTable = null)
+    public function writeStringTable(array $pStringTable = null)
     {
         if ($pStringTable !== null) {
             // Create XML writer
@@ -286,7 +286,7 @@ class StringTable extends WriterPart
      *
      * @return array
      */
-    public function flipStringTable($stringTable = [])
+    public function flipStringTable(array $stringTable)
     {
         // Return value
         $returnValue = [];
diff --git a/tests/PhpSpreadsheetTests/Worksheet/AutoFilterTest.php b/tests/PhpSpreadsheetTests/Worksheet/AutoFilterTest.php
index d1416b2d..7a943642 100644
--- a/tests/PhpSpreadsheetTests/Worksheet/AutoFilterTest.php
+++ b/tests/PhpSpreadsheetTests/Worksheet/AutoFilterTest.php
@@ -83,7 +83,7 @@ class AutoFilterTest extends \PHPUnit_Framework_TestCase
         $expectedResult = '';
 
         //  Setters return the instance to implement the fluent interface
-        $result = $this->testAutoFilterObject->setRange();
+        $result = $this->testAutoFilterObject->setRange('');
         $this->assertInstanceOf(AutoFilter::class, $result);
 
         //  Result should be a clear range
@@ -268,7 +268,7 @@ class AutoFilterTest extends \PHPUnit_Framework_TestCase
     public function testGetColumnWithoutRangeSet()
     {
         //  Clear the range
-        $result = $this->testAutoFilterObject->setRange();
+        $result = $this->testAutoFilterObject->setRange('');
         $result = $this->testAutoFilterObject->getColumn('A');
     }
 
@@ -282,7 +282,7 @@ class AutoFilterTest extends \PHPUnit_Framework_TestCase
         }
 
         //  Setters return the instance to implement the fluent interface
-        $result = $this->testAutoFilterObject->setRange();
+        $result = $this->testAutoFilterObject->setRange('');
         $this->assertInstanceOf(AutoFilter::class, $result);
 
         //  Range should be cleared