[1] Mainsoft was founded in 1993, mainly to propose integration products between Windows and other systems.

[2] Mainsoft was one of the main providers for the Microsoft Windows Interface Source Environment (WISE) program, a licensing program from Microsoft that allowed developers to recompile and run Windows-based applications on Unix and Macintosh platforms.

Instead Microsoft established partnerships to several software providers which in turn sold WISE SDKs to end-users.

[5] After the WISE program, Microsoft extended its agreements with Mainsoft to port Windows Media Player 6.3 and Internet Explorer to Unix.

To be able to develop WISE SDKs, software providers needed to have access to Windows internals source code.