> Some places surfaces this information to you, in various ways.

Citibank includes this code in the "SID" element in OFX generated by their "OFX Direct" service (i.e. https://www.accountonline.com/cards/svc/CitiOfxManager.do). I haven't seen it in the OFX from any other financial institution though. The codes are cataloged here: https://github.com/greggles/mcc-codes