The .xlsx is an open source filename extension format developed by Microsoft in collaboration with ISO/IEC and ECMA. It is part of the Open Document family of file formats. The .xlsx is associated with spreadsheet authoring applications particularly with Microsoft's Office Excel 2007 and above. The format has existed since 2005 and is also supported by several other proprietary and open source spreadsheet authoring software other than Microsoft's Office Excel. The xlsx format is the default filename extension for all spreadsheet documents produced using Microsoft Office Excel 2007 SP2 and above.