IPC is South America (100% sure of that). The PPT question has come up and I recall that there was a big problem with PPT (other than no service westward from PPT). Perhaps IPC-PPT was considered an ocean crossing; or it may have been the "no surface crossing of the pacific or atlantic ocean" rule (which meant you could not buy a separate non-oneworld ticket to "cross" the pacific), requiring return to SCL. Definitely some rule that made PPT very unattractive (but rules have changed so you'll have to research the current situation further, just be wary of initial findings).