what is the proper designation for this submunition? I've seen it variously described as 'PTAB 2.5', 'PTAB 2.5KO', 'PTAB 2.5 kilo', 'PTAB 85' or simply 'PTAB'... unsure as to which is correct, or if indeed PTAB refers to the entire weapon system (canister and bomblets) rather than just the submunition?? PTAB could also refer to the family of weapons developed from WW2 rather than specific model?

I have also read that there are two variants of this one pictured above, differing in the length of the tail?