Information technology — Document description and processing languages — Office Open XML File Formats — Part 3: Markup Compatibility and Extensibility

ISO/IEC 29500-3:2012 describes a set of conventions that are used by Office Open XML documents to clearly mark elements and attributes introduced by future versions or extensions of Office Open XML documents, while providing a method by which consumers can obtain a baseline version of the Office Open XML document (a version without extensions) for interoperability.