The Affinity Code is a legacy "internet code" used to tell people information about yourself. They're legacy, dating back more than a decade ago and were used primarily over Usenet and BBS systems back in the days when Wildcat held sway. They were codes used in signatures and posts which could be deciphered to give you a lot of information about a person.
It was like a short crypto.
Nowadays there's little use for them, but they're tradition so to speak.