

Main article: Standardization of Office Open XML

While Office 2013 and onward have full read/write support for ISO/IEC 29500 Strict, Microsoft has not yet implemented the strict non-transitional, or original standard, as the default file format yet due to remaining interoperability concerns. Microsoft Office 2013 and Microsoft Office 2016 additionally support both reading and writing of ISO/IEC 29500 Strict. Microsoft Office 2010 provides read support for ECMA-376, read/write support for ISO/IEC 29500 Transitional, and read support for ISO/IEC 29500 Strict. The format was initially standardized by the Ecma (as ECMA-376), and by the ISO and IEC (as ISO/IEC 29500) in later versions. Office Open XML (also informally known as OOXML) is a zipped, XML-based file format developed by Microsoft for representing spreadsheets, charts, presentations and word processing documents.
