Office Open XML (also informally known as OOXML or OpenXML) is a zipped, XML-based file format developed by Microsoft for representing spreadsheets, charts, presentations and word processing documents. The Office Open XML specification was initially standardised by Ecma (as ECMA-376) and later by ISO and IEC (as ISO/IEC 29500). Starting with Microsoft Office 2007, the Office Open XML file formats have become the default target file format of Microsoft Office.