GM transaxle ID tag code breakdown

ok, i already know which line means what (i.e. which line is transaxle, which is year model, which is model, etc... what i want to know is, what are the CODES? knowing which letter signifies which thing is great, but all i know is, my transmission is a "B" (i.e. 610RWB) - i know the 61 means it's a transaxle, the 0 means it's a 2000 model, the RW is the model number, & the B means it's a 4T65-E? i know W would be 4T60-E, but from the ident pictures i've seen, this trans is a 4T65-E.... i just wanted to verify with the id tag, but it seems as though it's some closely guarded secret or something....... anyone know?