OK, I think I have answered my own question and sorry for making a mess 
of the original question.  The question should have simply been: does 
the *forward* kinematics solver map joint positions to poses of the 
joints or the links?  Since the origins of joints and links need not 
coincide, I thought it could be one or the other.

Further experimentation seems to prove that the poses computed by get_fk 
are for the joints, not the links, although both the documentation and 
the output from get_fk use the word "Link" to label the computed poses.

Do I have this correct?

Thanks!
patrick