Microsoft Word is a word processor and was previously considered the main program in Office. Its proprietary DOC format is considered a de facto standard, although Word 2007 can also use a new XML-based, Microsoft Office-optimized format called .DOCX, which has been standardized by Ecma International as Office Open XML, and its SP2 update supports PDF and a limited ODF. Word is also available in some editions of Microsoft Works. It is available for the Windows and OS X platforms. The first version of Word, released in the autumn of 1983, was for the MS-DOS operating system and had the distinction of introducing the mouse to a broad population.