I know it's not relevant to you, Helene, and I totally understand your reasoning.
Unfortunately, in the ACBL, in 1990 when Announcements came out (or in 1991, when they revised them, can't remember now), they said:
Quote
After a 1NT forcing or semi-forcing response to a 1♥ or 1♠ opening bid with no interference.
Example: 1♥-P-1NT
The opening bidder will say aloud, "Forcing" or "Semi-forcing," if there was no other meaning attached to the agreement (such as showing four or more spades).
Of course, they never defined "semi-forcing", and for 30 years, people who thought they played this (or equivalently, the people who played "1NT forcing by passed hand, assuming you didn't open third-seat-light" - wherein lies the problem) would Announce "semi-forcing", and their opponents who didn't play it wouldn't understand (and their opponents who did play it frequently didn't play it the same way, so didn't get it right).
This, for an agreement that is supposedly so common and unforgettable and immediately understandable that it should be turned into an Announcement, is - bad.
And the announcement was pulled in whole hog into the new rules (adding only the Flannery-change "could have four spades"). So I commented that nobody knows what Semi-forcing means, it should probably be defined. They said "yes, it should, oops" and defined it.
So, at least in the ACBL, we now know what each other are talking about.
And the difference between this and the good old NF 1NT is that Kxx QTxx xx AJxx is a 2
♣ response in standard, and a semi-forcing 1NT response for those who play it. Obviously, both systems would pass 1NT with a hand that would prefer to play 1NT opposite a 3-card limit raise; but the NF NTers would pass with hands that would prefer to play 2
♠ or 4
♠ opposite a 3-card limit raise, too, because partner won't have that.
If you invite with Invitational hands, and don't bid 1NT with them, you're not playing "semi-forcing" 1NT response. If you put (some) invites into 1NT, then you are, and you so Announce. Like any jargon, using it outside its known space (like for instance Australia) where others may not have the same grounding in the jargon will lead to confusion, so (as I started), I agree with you for not using it.
If I was putting fenceposts, I would actually drive this one between the two. A SA-style "NF" 1NT response to 1
♠, putting the 3-card-LRs into some other call, "suggests 1NT as the final contract". A Semi-Forcing 1NT response does not (it "accepts that it may be the final contract", but it's not a suggestion). But I just enforce the rules, I don't interpret them, so take my opinion as just that.
When I go to sea, don't fear for me, Fear For The Storm -- Birdie and the Swansong (tSCoSI)