Microsoft has allowed developers to examine source code for .Net Framework libraries - provided they upgraded to the newly released Visual Studio 2008 software development platform. The company first proposed the move last October.

Developers, working through the .Net Reference Source project, will be able to view and debug the source code with the .Net Framework license in a read-only format. Among the software projects covered by the arrangement are: The .Net Base Class Libraries - including System, System.CodeDom and System.ComponentModel, ASP.Net - including System.Web.Extensions, Windows Forms, and Windows Presentation Foundation. Also offered are ADO.Net and XML.

"We think that enabling source code access and debugger integration of the .Net Framework libraries is going to be really valuable for .Net developers," said Scott Guthrie, general manager of the Microsoft developer division, in his blog. "Being able to step through and review the source should provide much better insight into how the .Net Framework libraries are implemented and in turn enable you to build better applications and make even better use of them."

Additional framework libraries are to be added in coming weeks and months, including LINQ (Language Integrated Query) and Windows Communication Foundation. Instructions on accessing the code can be found in another blog, that of Shawn Burke, a director in the Microsoft developer division.

Access to the code originally was expected to happen by last month. But Microsoft decided to continue taking feedback from developers and postponed the release until this month, a Microsoft representative said. When Microsoft first revealed its code access plans, it was characterised by analyst Greg DeMichillie, of Directions on Microsoft, as not an earth-shattering move now that open source is so prevalent.

Visual Studio 2008 became available at the end of November. Microsoft did not yet have current figures on shipment volumes for the platform this week.