phi files set the hierarchy of body parts , and using that file poser creates a bone structure for you and allocates the parts to the bones.  All thats left is the joint tweaking or setting centers for rotation if you are doing machines.   Much nicer than trying to draw bones in the right places manually.     I use it mainly for machinery so once its run I only have centers to set , and set limits and hide dials .

The hierarchy editor is close to what phi files do.