OK, so the next 'Duh' questions are: why are they called 1P and 2P? And why 1K not 100K when K usually represents Kilo which is 1000, i.e. 1 Kg = 1000 g.
A thread from back in 2000 that's still pretty accurate at explaining this:
http://www.flyertalk.com/forum/showthread.php?t=90499
