Microsoft is to share blueprints for its Windows operating system and .NET server software with approximately 150 systems integrators. To be eligible, the systems integrator must either be a Microsoft Gold Certified Support Partner or have at least 1,500 seats of Windows and a level A or B Premiere Support agreement.

Last May, Microsoft unveiled its Shared Source Initiative (SSI) to make source code available selectively, while still preserving intellectual property rights. The company has since expanded the program to include other entities — like national and state governments as well as other operating systems such as Windows CE.

Several analysts have labelled the move a defensive strategy against open source initiatives such as Linux which have made it easy for systems integrators to build custom software.