Modern Software Experience



Microsoft has released some Office Binary Formats as announced.


The specifications are provided in both PDF and XPS format.


The specifications are released under the Microsoft Open Specification Promise (OSP).

what (not)


These are specifications for the file formats of the core Office applications only; the formats being made available are those for Word, PowerPoint, Excel and Office Draw. The 2008-01-17 post Microsoft to release Office Document Formats goes into some of the reasons behind’s Microsoft public release of these Office document specification under the OSP.

version limited

The provided documentation is version limited. It does not provide full documentation for all versions, but, as the file names for the specification already suggest, only for Office 97 and later.


Microsoft may not want to support older versions, but some documentation for these versions is available from another source, namely the OpenOffice project.


Neither the old MDB nor the new ACCDB file format used by Microsoft Access is provided.

File formats for Microsoft Mail or Microsoft Schedule+ are not provided either, but these were replaced by Microsoft Outlook. Alas, the file format for Microsoft Outlook is not provided.

The MIX file format used by PhotoDraw is not provided.

The file formats for Microsoft Publisher is not provided.

The file format for Visio is not provided either.

third-party documentation

Links to third-party documentation for Office formats, including formats not documented by Microsoft are provided in the new Resource: Office File Formats.