Microsoft's Rich Signature (undocumented)

In this article I'm going to try to provide documentation for the undocumented Rich Signature produced by Microsoft compilers. I'm not completely sure when this signature was introduced, I wrongly believed that I had been introduced with Visual Studio 2003, but I was shown that it is present even in VC++ 6 executables. So, I guess this signature has been introduced with that compiler. Information about this topic is non-existent (seems strange, but it's a fact). Thus, most readers probably don't know what I'm talking about.

Link:
http://ntcore.com/Files/richsign.htm