There's no problem doing it from parallel waves. I noticed that there's a snapshot record for Percolate But from parallel waves.

But I can't figure out how to do it from other formations (e.g. facing lines or outfacing lines). I made a snapshot record for Percolate But from outfacing lines, but CSDS still doesn't extrapolate when I enter Percolate But (something else, like recycle). Is there some trick to making a snapshot record that's used in a parameterized call?