Looks like it's an old naming convention of theirs: https://msdn.microsoft.com/en-us/library/ms173075(v=vs.80).aspx https://msdn.microsoft.com/en-us/library/ms

Looks like it's an old naming convention of theirs: https://msdn.microsoft.com/en-us/library/ms173075(v=vs.80).aspx https://msdn.microsoft.com/en-us/library/ms173075(v=vs.80).a... At least as far back as Visual Studio 2005.