Okay, Tony. You got me. I guess I should've said "...used for RS-232
communication."
Or would it be RS-432? :P
RS-4xx for almost all xx seems to end up being
a serial protocol. RS-422/RS-423/RS-449 (and
obviously RS-232) seem to be the most common
ones but there seems to be a fair number of relatively
obscure ones too.
Antonio