These are both functions of your soloing system, meant to allow you to listen to one channel while not forcing you to chage the mix in any way or interupting any routing. In solo you can "solo" a track and hear it in a non desructive manner, keeping the session moving.

PFL stands for pre fade listen, usually a solo of the mic pre amp before the EQ stage. Any adjustments made to the faders or the EQs will not be heard when your are in PFL. PFL is most useful for setting levels of the mic preamp.

AFL is after fade listen. This allows you to hear changes in EQ and fader levels. AFL allows you to solo a channel (or channels) to make level changes on the faders and adjustments on the EQ.

fantastic. thank you.

Yeah, thanks, Kurt. It's damn handy to know (now) why the manual sez to set levels in PFL!