Microsoft Open Specification Promise

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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.[1]

The OSP is not a licence, but rather a covenant not to sue.[2] 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.[3]

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."[4]

GNU/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."[5][6]

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."[7]

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[8]

" permits implementation under free software licenses so long as the resulting code isn't used freely."[9]

Their analysis warned of a possible inconsistency with GPL.[9] 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.[10] 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."[9]

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.[9]

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".

In another, it specifically only mentions the "developers, distributors, and users of Covered Implementations", so excluding downstream developers, distributors, and users of code later derived from these "Covered Implementations"[9] and it specifically does not mention which version of the GPL is addressed, leading some commentators to conclude that the current GPLv3 may be excluded.[11]

Q: I am a developer/distributor/user of software that is licensed under the GPL, does the Open Specification Promise apply to me?
A: Absolutely, yes. The OSP applies to developers, distributors, and users of Covered Implementations without regard to the development model that created such implementations, or the type of copyright licenses under which they are distributed, or the business model of distributors/implementers. The OSP provides the assurance that Microsoft will not assert its Necessary Claims against anyone who make, use, sell, offer for sale, import, or distribute any Covered Implementation under any type of development or distribution model, including the GPL.[12]

Licensed technologies

Technologies on which the Open Specification Promise applies are:[1][13]

Web Services


  • OpenService Format Specification (a.o. Accelerator)
  • Web Slice Format Specification introduced with Internet Explorer 8
  • XML Search Suggestions Format Specification

Virtualization Specifications

  • Virtual Hard Disk (VHD) Image Format Specification
  • Microsoft Application Virtualization File Format Specification v1
  • Hyper-V Functional Specification[14]


  • RFC 4406 – Sender ID: Authenticating E-Mail
  • RFC 4408 – Sender Policy Framework: Authorizing Use of Domains in “Mail From”
  • RFC 4407 – Purported Responsible Address in E-Mail Messages
  • RFC 4405 – SMTP Service Extension for Indicating the Responsible Submitter of an E-Mail Message
  • RFC 7208 – Sender Policy Framework (SPF) for Authorizing Use of Domains in Email[15]
  • U-Prove Cryptographic Specification V1.0
  • U-Prove Technology Integration into the Identity Metasystem V1.0

Office file formats

XML file formats

  • Office 2003 XML Reference Schemas
  • Office Open XML 1.0 – Ecma-376
  • Office Open XML ISO/IEC 29500:2008
  • OpenDocument Format for Office Applications v1.0 OASIS
  • OpenDocument Format for Office Applications v1.0 ISO/IEC 26300:2006
  • OpenDocument Format for Office Applications v1.1 OASIS

Binary file formats

  • Word 97-2007 Binary File Format (.doc) Specification
  • PowerPoint 97-2007 Binary File Format (.ppt) Specification
  • Excel 97-2007 Binary File Format (.xls) Specification
  • Excel 2007 Binary File Format (.xlsb) Specification
  • Office Drawing 97-2007 Binary Format Specification
Structure specifications
  • [MS-DOC]: Word Binary File Format (.doc) Structure Specification
  • [MS-PPT]: PowerPoint Binary File Format (.ppt) Structure Specification
  • [MS-XLS]: Excel Binary File Format (.xls) Structure Specification
  • [MS-XLSB]: Excel Binary File Format (.xlsb) Structure Specification
  • [MS-ODRAW]: Office Drawing Binary File Format Structure Specification
  • [MS-CTDOC]: Word Custom Toolbar Binary File Format Structure Specification
  • [MS-CTXLS]: Excel Custom Toolbar Binary File Format Structure Specification
  • [MS-OFORMS]: Office Forms Binary File Format Structure Specification
  • [MS-OGRAPH]: Office Graph Binary File Format Structure Specification
  • [MS-OSHARED]: Office Common Data Types and Objects Structure Specification
  • [MS-OVBA]: Office VBA File Format Structure Specification
  • [MS-OFFCRYPTO]: Office Document Cryptography Structure Specification

Windows compound formats

  • [MS-CFB] Windows Compound Binary File Format Specification

Graphics formats

  • Windows Metafile Format (.wmf) Specification
  • Ink Serialized Format (ISF) Specification
  • JPEG XR (.jxr) Format

Microsoft computer languages

  • [MS-XAML]: XAML Object Mapping Specification 2006 (Draft v0.1)
  • [MS-XAML]: XAML Object Mapping Specification 2006 (v1.0)
  • [MS-WPFXV]: WPF XAML Vocabulary Specification 2006 (Draft v0.1)
  • [MS-WPFXV]: WPF XAML Vocabulary Specification 2006 (v1.0)
  • [MS-SLXV]: Silverlight XAML Vocabulary Specification 2008 (Draft v0.9)


  • Decentralized Software Services Protocol – DSSP/1.0


  • FeedSync v1.0, v1.0.1

Windows Rally Technologies

  • Windows Connect Now – UFD and Windows Vista
  • Windows Connect Now – UFD for Windows XP

Published protocols

In Microsoft's list of covered protocols there are many third-party protocols which Microsoft did not create but for which they imply they have patents which are necessary for implementation[citation needed]:

See also


  1. ^ a b "Microsoft Open Specification Promise". Retrieved 2007-11-02.
  2. ^ "Microsoft's Open Specification Promise Eases Web Services Patent Concerns". Retrieved 2015-04-18.
  3. ^ Richard Wilder (Associate General Counsel for Intellectual Property Policy at Microsoft) (2008-07-25). "The OSP and You". Port 25 (Microsoft's open source portal). Retrieved 2008-07-25.
  4. ^ "Microsoft's Open Specification Promise Eases Web Services Patent Concerns". 2006-09-12.
  5. ^ "Microsoft Open Specification Promise".
  6. ^ "Microsoft promises to hang patent fire over web services". 2006-09-12.
  7. ^ Peter Galli (2006-09-12). "Microsoft Promises Not to Sue over Web Services Specs".
  8. ^ "Software Freedom Law Center Publishes Analysis of Microsoft's Open Specification Promise". Software Freedom Law Center. March 12, 2008.
  9. ^ a b c d e "Microsoft's Open Specification Promise: No Assurance for GPL". Software Freedom Law Center. 2008-03-12. Retrieved 2008-03-30.
  10. ^ "GNU General Public License (Version 3, 29 June 2007)". Free Software Foundation. 2008-02-12. See section 11 for patents.
  11. ^ Bilodeau, J-F (March 19, 2008). "Three Things Microsoft Should Do". Archived from the original on February 27, 2010. Retrieved 2009-09-16. Use the GNU GPL 3: Most free software is released under the GNU GPL 2 or 3, which is incompatible with Microsoft's OSP (Open Specification Promise) and the Ms-PL (Microsoft Public License). This is not an accident. Microsoft does not want software written using their technology to spread to other platform. Again, it's vendor lock-in. If Microsoft truly wanted to work with the Open Source community, they should abandon the OSP and the Ms-PL for the GPL, or another OSI certified license.
  12. ^ Microsoft Open Specification Promise - Frequently Asked Questions
  13. ^ Microsoft Office Binary (doc, xls, ppt) File Formats Archived April 30, 2008, at the Wayback Machine
  14. ^ Hypervisor Functional Specification
  15. ^ Retrieved 1014-05-08.

External links

Edited: 2021-06-18 15:10:01