I believe it's initials for 'population, belt, gas giant' in the extended UWP codes. It predates Mongoose Traveller, but I'm not sure where it was first implemented.
Do you know how to read them?
I thought it was a step down from a BFG.
'B' and 'G' are simply the number of belts and gas giants in system. 'P' is a bit more fiddly. It's the number you multiply times 10 raised by the UWP population number for the total world population. So a world with a UWP A123456-7 and a 'P' level of 8 would have a population of 4x10^8. Assuming I remember UWP code correctly that is.A little research turns up that it was first implemented in "The Spinward Marches Campaign" boxed set put out by GDW in the mid 80s.
Close.The "P" is the first digit in the Population number, while the POP info in the UWP is the magnitude of the population.In Ndege's example, the population of the world in question would be 8000, from the POP of 4 giving it in the 1000s, and the "P" giving it an 8.Make sense?
Oops! Yeah, got that exactly backwards in my example. It should be 8x10^4
Although by my calculations (actually my computer's) that would work out to a population of 80,000.