I have no idea what the 'sl' line does either. The rest of your interpritation seems to be correct. The 'Loop' setting is NOT saved to pz3, or pz2. I am quite certain of this in P4, and though I have not tested this in other versions, I suspect the same holdes true. It's interesting to note that there are 'loopStart' and 'loopEnd' lines in the 'movieInfo' section of the pz3. If, for example, you set 'loopStart 5' and 'loopEnd 7, Poser will only play k frames 5 through 7, irrespective of wether 'Loop' is set on or off. Also note that these will display in the interface as frames 6 through 8. In library files the k frame numbers start at 0, but in the interface 'k 0' is represented as frame 1. P.S. I just added the above trivia because I have nothing really usefull to say.