Forcing raises

These days most of us are brought up on the notion that a raise of partner's suit is inherently non-forcing.  This is all the more so when there has been intervention by the opponent.  And a preference not only is not-forcing but it warns that opener would be well advised not to bid again.

But re-reading Barry Rigal's excellent book Test your Bridge Judgement has helped solidify an idea that's been rattling around my brain for a while now.  Incidentally, this book is one of the best – and most thought-provoking – bridge books I know.  I would put it in my top ten.

The situation arises in the following circumstances.  Opener bids 1 banana, let's say.  For now, we'll assume that it's a major but the same idea applies (though typically with an extra card in support) for a minor suit.  Partner makes a bid that does not deny three bananas, but is otherwise forcing for one round.  Opener now makes a bid which is invitational and partner now raises bananas.  That raise is forcing.  At least that's what I'm asserting here.

Let's see an example in action (this is actually the one from Rigal's book in the chapter called Split Ends).  You hold ♠A9753 ♥A6 ♦A843 ♣KQ.  You open 1♠, LHO passes and partner bids a forcing 1NT.  RHO passes and you make a generally balanced invitation with 2NT.  Partner now raises to 3♠.  By bridge logic, this is forcing.  Partner has three spades but he didn't bid 2♠ at his first turn.  His 1NT was therefore based on either a really bad flat hand with three spades or a hand that was going to make a three-piece limit raise, i.e. extras.  Clearly, he has the latter hand because with the former he would simply pass 2NT.

So both partners have an invitational hand and therefore each would accept a game invitation.  Therefore, 3♠ must be forcing.  Another way to look at it is this:  opener has made an invitation, not knowing that responder has support.  When that support is now revealed, it is good news, so it's hard to imagine passing.

Here's another example, Distracted Choice from the same book.  You open ♠AJ3 ♥K7653 ♦96 ♣AQJ with 1♥ in third seat and partner bids a natural 2♣.  You know he has 10-12 hcp and decent clubs but he hasn't denied three hearts.  If you had a minimum hand you might pass.  But with just a little more than that, you raise to 3♣, obviously forward going.  Partner now shows his three-card support with 3♥, or at least it should be three cards.  Again, partner has given you the best possible news (he could have passed 3♣) so there's absolutely no reason to pass.  We bid 3♠ which at this point obviously just shows some fragment for notrump purposes and partner bids 4♣ and we sign off in 4♥.  In the story, it turns out that partner only has ♥QJ and it takes all of Barry's skill to make the contract.  I'm afraid I would have gone down with trumps splitting 4-2.

So sometimes, raising partner's suit is non-forcing and sometimes it's forcing.  Are there other situations that I'm missing?  Any other comments?