Microsoft promises that it would not pursue patent claims against the open source implementation of C# programming language and Common Language Infrastructure (CLI).

The company said that the third party implementations of C# and CLI will be extended in its Community Promise, offering legal assurance to the users of open source Mono implementations.

Peter Galli, open-source community manager of Microsoft, said in a blog post: “Microsoft will be applying the Community Promise to the ECMA 334 and ECMA 335 specs.”

The ECMA 334 reportedly specifies the form and establishes the interpretation of programmes written in C# language and the ECMA 335 is a standard that is said to define the CLI in which application written in multiple high-level languages can be executed in different system environments without the need to rewrite the applications to consider the characteristics of those environments.

Under the Community Promise, the company gave assurance that it will not assert its Necessary Claims against anyone who makes, uses, sells, offers for sale, imports, or distributes any Covered Implementation under any type of development or distribution model. This includes open-source licensing models such as the LGPL or GPL.

The company said that the third parties are free to implement these specifications with their technology, code and solutions with out singing a license.

Scott Guthrie, corporate vice president for the .Net developer platform, said: The Community Promise is an excellent vehicle and, in this situation, ensures the best balance of interoperability and flexibility for developers.”

The Community Promise reportedly applies to developers, distributors and users of Covered Implementations without regard to the development model that is used to create the implementations.