Ockham has made a python script that checks for existing pngs and then delete all the unneeded rsr's :) Great little script. As it has been said, do NOT delete POSER.RSR! In fact it is a really good idea to write protect that file so that it doesn't get deleted, overwritten or otherwise corrupted. It is a vital part of the Poser program. But both PPP and P5 are happy without any other rsr's than that one :o) (of course after the necessary pngs has been created)

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.