I've been studying the guts of the CR2 for a while now; I got into it because I was having a ton of trouble rigging figures, and I thought, me being a programmer and all, that it would be much simpler to go "under the hood" and edit the data files directly. I have since learned that "simple" is not a word to apply to the CR2 file. It still seems odd to me the way that bones are stored in the file; I got into it expecting the bones to be their own data object, and I found the structure a little elusive.

I'm pretty sure that some of the components of the file are obsolete, and just kept in place because Poser's file parser expects them to be there, even though they no longer perform any actual function.