The ACBL Alert Chart says:
In general, when the use of conventions leads to unexpected understandings about suit length by negative inference, a natural call becomes Alertable. Some such agreements have become expected and are fairly common, therefore no Alert is required.
Flannery is such a common convention over here - especially in Calgary, where "with or without Flannery" seems to be the first query in *pickup* discussions, and most people are upset when I say "without" - that it is the first "people will expect it" example on the ACBL Alert Chart, even before 1H-1NT(forcing); 2m on 3 cards (or 2C on 4522) min.
So, as everyone has said, in ACBL-land, 1H-1S promising 5 is not alertable, nor is 1H-1NT concealing a 4-card spade suit. This happens to be one of my "uncomfort zones" with the Alert chart, because while it is very common, the trigger for the information isn't in the auction, but in a totally different call, so it could very easily be a "surprise", especially if (as is very common here, grumble) there are no CCs on the table. But I don't decide the system, I just rule on and teach it.
Michael. [1 edits; Last edit by mycroft at 21:28:17 Mon Jul 7 2003]