The link in the "Publicly Available Information on the file formats" on the "Contribution Guidelines" page (https://poi.apache.org/guidelines.html) of teh Apache POI Website is broken. The link presented to http://www.microsoft.com/interop/docs/OfficeBinaryFormats.mspx no longer points to a valid address.

The file format documentation is available online and for download at a new address: http://msdn.microsoft.com/en-us/library/cc313118.aspx