The Rich Header was presumably introduced by Microsoft in a previous version of Visual Studio. What was its original purpose and how does it achieve this? Is DanS the designer, similar to MZ?
The Rich header is described in detail in this article by Daniel Pistelli. It contains identifiers for all the (Microsoft) compilers and related tools used to build the object files which end up in the executable, with a count of object files for each. It goes at least as far back as Visual C++ 6 (1998) and is placed in executables (including DLLs) by the Microsoft linker.
Its purpose isn’t documented; presumably it was introduced so that an object file’s producer could be determined after the fact, e.g. to debug build problems which aren’t immediately apparent, or track changes in object output back to their origin.
DanS might be the designer; a candidate is Dan Ruder, who wrote an article on dynamic linking published in the 1993 MSDN Library, but others disagree, suggesting instead Richard Shupak and Dan Spalding.
See also the Rich Header Research repository.