Attached Link: Link to an old 2001 review of Pro Pack

Poser Pro Pack came between Poser 4 and Poser 5, like lesbentley said it added python scripting and the main point of it was the plugins for exporting (to host your scene) poser scenes in Lightwave, 3D Studio Max and Cinema 4D...  It worked ok, I rather liked (at the time) that I could finally have fully textured (did need the fix_falloff script for transparencies to show up properly) and animated poser scenes in MAX with litlle fuss or messing around. 

Gerard

The GR00VY GH0ULIE!

You are pure, you are snow
We are the useless sluts that they mould
Rock n roll is our epiphany
Culture, alienation, boredom and despair