[kaushiks]

Not necessarily. As long as it wasn't related to the JIT or the GC, one could always look up the SSCLI (ROTOR) code to understand how something was implemented. https://en.wikipedia.org/wiki/Shared_Source_Common_Language_...

[MarkSweep]

That's a good point. It's fun to diff Rotor and CoreCLR to see how much has changed and what has stayed the same. The JIT and GC seem to not match up at all, but good chunks of the vm folder match up nicely.