Joe is not a nickname for Joseph, neither is Dan a nickname for Daniel, Tom for Thomas, etc. They're versions of the actual names. Nicknames, per se, were never part of this conversation. I go by the shorter version professionally and personally, and accept that I have to use the formal version for certain legal applications, like TSA. But as another poster points out, it appears that AA is changing the rules, at least when it comes to paying for award fees.