It is new pension speak (i.e. AFPS 05) for Immediate Pension Point which under the old system was your 16/38 or 22 years for Airmen; under the new Scheme it is 18/40 for all. Link below will give you more guidance:
http://www.mod.uk/NR/rdonlyres/A2D4F...rt2_amend2.pdf
Attended a very interesting brief from the Forces Pension Society recently; if you have any questions/doubts issues about your pension you may wish to consider joining - their web address is
The Forces Pension Society