Partners will be able to examine the Visual Studio (VS) integrated development environment (IDE) source code and create add-ons to the IDE for cross-platform development under new licensing rules. The less restrictive rules will help partners understand how the IDE works and help them debug add-ons, and remove a barrier that would otherwise force add-on developers to choose an alternative development environment, such as the open source Eclipse IDE.

The new rules will particularly aid partners building Visual Studio add-ons targeting platforms other than Microsoft's, such as Java or the Symbian mobile phone platform. The change could help increase sales for VS, particularly for the more expensive Team System editions, because corporate developers with mixed environments are unlikely to consider Team System if it doesn't support all of their development projects. The move suggests that Visual Studio, and in particular Team System, is now an important business in its own right rather than merely a way to encourage developers to build applications for Windows.

Access to the IDE source code will be limited to premier members, the top level of the Visual Studio Industry Partners (VSIP) program, under the terms of Microsoft's Reference Licensing Program, which is also used to provide developers with access to the source code of the .NET Framework. Partners will be able to read but not modify or redistribute the code.

The various levels of the VSIP program are described in "VSIP Tiers" on page 20 of the June 2005 Update.

The VSIP home page is msdn2.microsoft.com/en-us/vstudio/aa700860.aspx.