I think that Poser 4 Pro Pack was an improved version of Poser 4 that included for the first time the use of Python scripts.  I think.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

Poser Pro 2012, SR2, Paintshop Pro 8