I’ve never looked at the Blender source code, but I’m a professional C++ developer. I’m not 100% sure that I understand your question though.
Are you trying to determine, for example, how a “Size” or “Displacement” is coded from a memory perspective? If so I can take a peek at the source and see if they are defined in some central place that I can point you to.
Or are you asking more like “what is an unsigned integer?” or “what is a boolean?” If this is more your question then a good place to start is here: https://www.geeksforgeeks.org/c-data-types/
