diff --git a/src/PhpSpreadsheet/Style/NumberFormat.php b/src/PhpSpreadsheet/Style/NumberFormat.php
index 0ccf7f68..98de69dd 100644
--- a/src/PhpSpreadsheet/Style/NumberFormat.php
+++ b/src/PhpSpreadsheet/Style/NumberFormat.php
@@ -245,6 +245,28 @@ class NumberFormat extends Supervisor implements \PHPExcel\IComparable
      */
     private static function fillBuiltInFormatCodes()
     {
+        //  [MS-OI29500: Microsoft Office Implementation Information for ISO/IEC-29500 Standard Compliance]
+        //  18.8.30. numFmt (Number Format)
+        //
+        //  The ECMA standard defines built-in format IDs
+        //      14: "mm-dd-yy"
+        //      22: "m/d/yy h:mm"
+        //      37: "#,##0 ;(#,##0)"
+        //      38: "#,##0 ;[Red](#,##0)"
+        //      39: "#,##0.00;(#,##0.00)"
+        //      40: "#,##0.00;[Red](#,##0.00)"
+        //      47: "mmss.0"
+        //      KOR fmt 55: "yyyy-mm-dd"
+        //  Excel defines built-in format IDs
+        //      14: "m/d/yyyy"
+        //      22: "m/d/yyyy h:mm"
+        //      37: "#,##0_);(#,##0)"
+        //      38: "#,##0_);[Red](#,##0)"
+        //      39: "#,##0.00_);(#,##0.00)"
+        //      40: "#,##0.00_);[Red](#,##0.00)"
+        //      47: "mm:ss.0"
+        //      KOR fmt 55: "yyyy/mm/dd"
+
         // Built-in format codes
         if (is_null(self::$builtInFormats)) {
             self::$builtInFormats = array();
@@ -261,7 +283,7 @@ class NumberFormat extends Supervisor implements \PHPExcel\IComparable
             self::$builtInFormats[11] = '0.00E+00';
             self::$builtInFormats[12] = '# ?/?';
             self::$builtInFormats[13] = '# ??/??';
-            self::$builtInFormats[14] = 'mm-dd-yy';
+            self::$builtInFormats[14] = 'm/d/yyyy';                     // Despite ECMA 'mm-dd-yy';
             self::$builtInFormats[15] = 'd-mmm-yy';
             self::$builtInFormats[16] = 'd-mmm';
             self::$builtInFormats[17] = 'mmm-yy';
@@ -269,17 +291,17 @@ class NumberFormat extends Supervisor implements \PHPExcel\IComparable
             self::$builtInFormats[19] = 'h:mm:ss AM/PM';
             self::$builtInFormats[20] = 'h:mm';
             self::$builtInFormats[21] = 'h:mm:ss';
-            self::$builtInFormats[22] = 'm/d/yy h:mm';
+            self::$builtInFormats[22] = 'm/d/yyyy h:mm';                // Despite ECMA 'm/d/yy h:mm';
 
-            self::$builtInFormats[37] = '#,##0 ;(#,##0)';
-            self::$builtInFormats[38] = '#,##0 ;[Red](#,##0)';
-            self::$builtInFormats[39] = '#,##0.00;(#,##0.00)';
-            self::$builtInFormats[40] = '#,##0.00;[Red](#,##0.00)';
+            self::$builtInFormats[37] = '#,##0_);(#,##0)';              //  Despite ECMA '#,##0 ;(#,##0)';
+            self::$builtInFormats[38] = '#,##0_);[Red](#,##0)';         //  Despite ECMA '#,##0 ;[Red](#,##0)';
+            self::$builtInFormats[39] = '#,##0.00_);(#,##0.00)';        //  Despite ECMA '#,##0.00;(#,##0.00)';
+            self::$builtInFormats[40] = '#,##0.00_);[Red](#,##0.00)';   //  Despite ECMA '#,##0.00;[Red](#,##0.00)';
 
             self::$builtInFormats[44] = '_("$"* #,##0.00_);_("$"* \(#,##0.00\);_("$"* "-"??_);_(@_)';
             self::$builtInFormats[45] = 'mm:ss';
             self::$builtInFormats[46] = '[h]:mm:ss';
-            self::$builtInFormats[47] = 'mmss.0';
+            self::$builtInFormats[47] = 'mm:ss.0';                      //  Despite ECMA 'mmss.0';
             self::$builtInFormats[48] = '##0.0E+0';
             self::$builtInFormats[49] = '@';