...that's P for LAVIII brakes. O is formal DND driver training.
Since you've all pulled the measuring tape out:A1, A6, B1, B5, C1, C11, C23, C26, C3, C53, C60, C61, C71, D1, D2, D3, D12, E1, E10, E20, E21, E23, E24, E25, E3, F4, F5, G16, G17, H10, H12, H20, H22, J11, T4, T6.
SPEC;A, B, C, E, F, H, L, M, N, O (that's airbrakes on real trucks, LOL), had a G but it has long expired and is no longer offered on base.
Oh, did I mentionI've got over 20years in the trade between field, base and wings? 8)
Cheers, BYTD