Agilent ads P_1 Tone

If I select P_1 tone from freq domain sources,

What is the difference between, P=polar(dbmtow(0),0) and Pac=polar(dbmtow(0),0)..?

Which value should i use.?

First is used for large signal HB simulations, second is used for small signal AC simulations.
Both shouldn't be defined simultaneously.Either P or Pac..