Finding Microsoft Office File Format Documentation
Summary: If you are creating a program that reads or writes files compatible with Microsoft Office applications, you need the appropriate Open Specifications documents. This article helps you locate the specifications that are most appropriate to your needs.
Published: December 2010
File Format Documentation on MSDN
The specifications for the .doc, .ppt .xls, and .xlsb file formats are freely available on MSDN. These file formats are used by versions of Microsoft Office prior to the release of the 2007 Microsoft Office system.
Documentation for Office Open XML
The applications in the 2007 Microsoft Office system and Microsoft Office 2010 use a file format called Office Open XML. Office Open XML is an industry-standard XML file format that is defined by international standards organizations. Multiple variations of the standard exist.
The first version of the Office Open XML standard was defined by the European Computer Manufacturers Association (ECMA) as Standard ECMA-376. You can view this for free on the ECMA web site.
The 2007 Microsoft Office system reads and writes files compatible with the ECMA-376 standard. They have the file name extensions .xlsx, .docx, and .pptx.
ISO/IEC 29500 and ECMA-376 2nd Edition
Office 2010 uses a newer version of the Office Open XML standard. This standard, known as ISO/IEC 29500, can be purchased from the International Standards Organization (ISO) web site. However, ISO/IEC 29500 is identical to a standard called ECMA-376 2nd Edition, which is available for free on the ECMA web site.
Like the 2007 Microsoft Office system, Office 2010 uses .xlsx, .docx, and .pptx as the file name extensions for its applications.