The Microsoft Open Specification Promise (or OSP) is a promise by Microsoft, published in September 2006, to not assert its patents, in certain conditions, against implementations of a certain list of specifications.
The OSP is not a licence, but rather a covenant not to sue. It promises protection but does not grant any rights.
The OSP is limited to implementations to the extent that they conform to those specifications. This allows for conformance to be partial. So if an implementation follows the specification for some aspects, and deviates in other aspects, then the Covenant Not to Sue applies only to the implementation's aspects which follow the specification.
Relations with free software / open source projects
The protections granted by the OSP are independent to the licence of implementations. There is disagreement as to whether the conditions of the OSP can be fulfilled by free software / open source projects, and whether they thus gain any protection from the OSP.
An article in Cover Pages quotes Lawrence Rosen, an attorney and lecturer at Stanford Law School, as saying,
"I'm pleased that this OSP is compatible with free and open-source licenses."
Linux vendor Red Hat's stance, as communicated by lawyer Mark Webbink in 2006, is:
"Red Hat believes that the text of the OSP gives sufficient flexibility to implement the listed specifications in software licensed under free and open-source licenses. We commend Microsoft’s efforts to reach out to representatives from the open source community and solicit their feedback on this text, and Microsoft's willingness to make modifications in response to our comments."
Standards lawyer Andy Updegrove said in 2006 the Open Specification Promise was
"what I consider to be a highly desirable tool for facilitating the implementation of open standards, in particular where those standards are of interest to the open source community."
However, the Software Freedom Law Center, a law firm for free software and open source software, has warned of problems with the OSP for use in free software / open source software projects. In a published analysis of the promise it states that "...it permits implementation under free software licenses so long as the resulting code isn't used freely."
Their analysis warned of a possible inconsistency with GPL. This applies specifically to the patent promise scope being limited to conforming implementations of covered specifications only.
Effectively when an implementer owns a patent and builds that patent technology in GPL3 licensed code, the implementer grants those first party patent rights downline to all re-users of that code. When the code is reused, the OSP only applies as long as the reuse of that code is limited to implementing the covered specifications.
Other patent promises with similar limitations include IBM's Interoperability Specifications Pledge (ISP) and Sun Microsystems' OpenDocument Patent Statement. This means, for example, that use of the required Sun patented StarOffice-related technology for OpenDocument should be protected by the Sun Covenant, but reuse of the code with the patented technology for non-OpenDocument implementations is no longer protected by the related Sun covenant.
For this reason the SFLC has stated: "The OSP cannot be relied upon by GPL developers for their implementations not because its provisions conflict with GPL, but because it does not provide the freedom that the GPL requires."
The SFLC specifically point out: new versions of listed specifications could be issued at any time by Microsoft, and be excluded from the OSP. any code resulting from an implementation of one of the covered specifications could not safely be used outside the very limited field of use defined by Microsoft in the OSP.
The Microsoft OSP itself mentions the GPL in two of its FAQs. In one it says, "we can’t give anyone a legal opinion about how our language relates to the GPL or other OSS licenses".