New to Ptolus, old school DND/PF player

Howdy all! I'm new to the Ptolus setting, but a long time player of DND and Pathfinder. I'm trying to find out more about character and NPC creation, and am really struggling to find some basic things, like a list of the Skills that a PC/NPC can have. Am I to assume that the list of skills is based on the preceeding DND content? Therefore original Ptolus would use DND 3.0 and the current would use 5E?