Seem to remember when I did my glider stuff that there was a 'B' certificate as well. Can't remember what it was for. To the OP, you can blag up to ten hours off your PPL, one for each ten hours you have as P1 on a glider. It might have something to do with having a silver as well. Anyway, when I did my PPL I got the allowance off.
But then again it might have all changed now under EASA...if you can keep up with it all you're a better man than me...