I have added some text at [[Commons:Project scope/Proposal#Pdf and Djvu formats]] dealing with these based on the discussion on the talk page. Users are by no means unanimous about which files should be allowed, and I have tried to follow the majority opinion. Thus, the suggestion is that if a Pdf or Djvu file is educationally useful even to a single other Wiki it should be kept. Would you like to comment before this page goes live? Please do so at the bottom of the talk page.
Regards,
Michael