7ER is the 757/767 except for the 767-400 (which is the 765, because, reasons). A is a captain, B is an FO.

I don’t know if a 4 person crew has ABCD or AABB, but I like to think there are 350Zs floating around. I wouldn’t know because I fly small narrow bodies with just two pilots and a couple flight attendants with an A line. Sometimes the A lines, and the other flight attendants, have A days. Lots of As…