In November 2003, Microsoft first posted an open and royalty-free license for the Office 2003 Reference Schemas.

Beginning in November 2005, Microsoft is offering a Covenant not to Sue for the Office 2003 Reference Schemas.

Individuals and companies wishing to implement programs that support the Office 2003 Reference Schemas are recommended to rely upon the Covenant not to Sue. The covenant is an irrevocable commitment by Microsoft that it will not assert patent rights against individuals or companies that implement programs that conform to the specifications for the Office 2003 Reference Schemas. It is subject to limited conditions, which are described in the covenant. Microsoft will also be offering this same covenant with respect to the forthcoming specifications for the "Office 12" schema specifications. More information about this program will be forthcoming at or before the time of the commercial availability of "Office 12."

Anyone who would prefer to rely upon the older open and royalty-free license for the Office 2003 Reference Schemas is welcome to do so.