Quote - The first link of the chain of bones turns relative to the body of the figure, perhaps this is where your error is, or do you mean by "first link" the body?

I was using a sort of muddled shorthand to communicate.    The BODY rotations are set to zero at start and the first link inherits rotational data which is in worldspace, not localspace.  The angles it processes are relative to UNIVERSE, then, and not relative to the BODY.

I'm using some matrix math involving the rest matrix (basically just the axis orientation, here, since we're in a straight line) of the actors to remove the rotation order problem.  That trick isn't working, however, for that base link.  I'm trying to work toward a process which avoids explicating the rotation orders or treats the axes differently.  Perhaps that is unavoidable at this point, however.  Hmm.

I'll have to think about how these ideas might help with the setup I have.  It's working, aside from that periodic problem with the base link.  I don't think I need a change of process, overall.  Just a procedure for the first link in the chain.

It sounds like you've dealt with something similar, in the past? 

===========================sigline======================================================

Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.