It's technically an Aztec code. It's also signed using RSA which means anyone with the public key files (which are not publicly available, though some for digital tickets have leaked*) can verify an Aztec code was issued by a real retailer, and to anyone without the key files it looks like random letters.
You're looking for details on the RSP (Rail Settlement Plan) code type 8 which is going to be almost impossible to find anything about online. Unless they use the same RSA keys as the leaked type 6 (digital tickets) ones then you have no chance of even trying to start figuring out what's on them.
At a guess, I'd say it's unlikely data of birth would be on there. Probably just the name, expiry, railcard type, issuing retailer, issue time, and whatever else they deem important!
*as only the public key has been leaked there is no risk of fraudulent tickets/railcards being created