Poser library files such as pz2 (pose), hd2 (hand pose), fc2 (face pose), cr2 (character), pp2 (prop), cm2 (camera), and lt2 (light), are script flies written in plain text, Poser creates them automaticly when you save a file from within the Poser interface, but you can create them in a text editor if you want. rsr files (resource fork) are binary files, they are used to contain the thumbnails for the pallets, and in Poser 4, to store a compressed version of the Wavefront Object files (*.obj). Normally you would let Poser create these.