jallerton, on 2011-December-17, 11:25, said:
On the other hand, if a pair agrees to play a forcing 1NT response, Opener is forced by the system to bid 2♣ on a 5323 or a 5233 shape. These represent a singificant proportion of 2♣ rebids in this sequence. I play this system with one partner. My opponents might reasonably expect an unalerted 2♣ bid to show 4+ clubs in this sequence, and I therefore alert 2♣ when it comes up.
I think this sequence depends a bit on the opponents. If I don't know them, or I know that they aren't used to forcing 1NT, I would always alert 2C because the 3-card suit would come as a surprise. Against people who are used to the forcing 1NT, I wouldn't alert it because they know that fits completely in with "ostensibly natural that may on occasion only contain three cards". I would alert, of course, if I always rebid 2C without a side 4-card suit so it can be 5332.