Here in BNA our codes are not printed on the releases but they are for the doors at ORD and we are not allowed to give them to pilots but rather open the door for them. We actually had a guy come close to getting fired for giving the code to a pilot. I also don't think its a good idea to let everyone know that these codes are printed in your release. It wouldn't take a very bright criminal to get one of those. We useually have 2 or 3 printed out in the jetbridge for the next few flights out of that gate.