mycroft, on 2021-November-04, 11:16, said:
5-card Stayman: Ah, but not in ACBL or NZ at least (not sure about Oz). Explicitly so that opener can't tell responder what his rebid will mean by Alert of lack thereof. If both are Alertable because "simplicity", of course, then we're back in the same boat.
2C is not alertable in Oz, but the responses are unless it is 2M showing 4+ cards in that suit.