To add to what Coryphaeus said:

by Kees_B Moderator - 1/6/13 5:00 AM

In Reply to: Opening a PFF file extension by craigflaa

http://filext.com/alphalist.php?extstart=^P gives 7 possibilities. And that doesn't include the possibibility that the list isn't complete.
So the best thing to do is to ask the maker of the file.

Kees