PhpSpreadsheet/tests/data/Shared/Date/FormatCodes.php

<?php

//  Excel Format Code                     Result
return [
    [ 'General',                          false ],
    [ '@',                                false ],
    [ '0',                                false ],
    [ '0.00',                             false ],
    [ '#,##0.00',                         false ],
    [ '#,##0.00_-',                       false ],
    [ '0%',                               false ],
    [ '0.00%',                            false ],
    [ 'yyyy-mm-dd',                       true  ],
    [ 'yy-mm-dd',                         true  ],
    [ 'dd/mm/yy',                         true  ],
    [ 'd/m/y',                            true  ],
    [ 'd-m-y',                            true  ],
    [ 'd-m',                              true  ],
    [ 'm-y',                              true  ],
    [ 'mm-dd-yy',                         true  ],
    [ 'd-mmm-yy',                         true  ],
    [ 'd-mmm',                            true  ],
    [ 'mmm-yy',                           true  ],
    [ 'm/d/yy h:mm',                      true  ],
    [ 'd/m/y h:mm',                       true  ],
    [ 'h:mm AM/PM',                       true  ],
    [ 'h:mm:ss AM/PM',                    true  ],
    [ 'h:mm',                             true  ],
    [ 'h:mm:ss',                          true  ],
    [ 'mm:ss',                            true  ],
    [ 'h:mm:ss',                          true  ],
    [ 'i:s.S',                            true  ],
    [ 'h:mm:ss;@',                        true  ],
    [ 'yy/mm/dd;@',                       true  ],
    [ '"$" #,##0.00_-',                   false ],
    [ '$#,##0_-',                         false ],
    [ '[$EUR ]#,##0.00_-',                false ],
    [ '_[$EUR ]#,##0.00_-',               false ],
    [ '[Green]#,##0.00;[Red]#,##0.00_-',  false ],
    [ '#,##0.00 "dollars"',               false ],
];