Introduction to the Open XML Format

Getting to know the Open Document Format



By learning how a document is constructed, you understand why there is no other way to add your custom ribbon in such a complicated way.


Since Office 2007 Microsoft introduced a new file format, mostly ending with an X:

  • .docx instead of .doc for Word documents
  • .xlsx instead of .xls for Excel documents
  • pptx instead of .ppt for Powerpoint documents


This new document format adheres to an open standard. In essence these files are a collection of compressed directories containing special .xml-files. The method used for compression is a standard ZIP-compression. These files can be decompressed using 7zip, WinZip or simply Windows itself. You only need to replace the extension with 'zip', and in most cases you can unpack them. If you have shell-integration of 7zip turned on, you can easily use the right mouse button in the Windows Explorer to directory unpack them into a directory.


You now have some basic knowledge of how an Office document is internally structured. Next step is to make some changes.

Copyright 2013 Martin Molema