I had this auction today in an ACBL Robot IMP Tournament
P 1S 3C 4C (me)
P 4S P
Here is the definition of 4S: 5+♠; 11-21 HCP; 12-22 total points.
Honestly, I don't think GIB actually bids in accordance with this definition, and would move toward slam with hands near or at the top of the stated range. I certainly hope that is the case! Obviously this definition is nonsense and should be a high priority for change.
It was easier for me since I held 13 HCP and knew partner had no more, even though slam was still possible. I don't think the definition would be any different in GIB formats where "Human Best Hand" is not used, though.
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A Very Poor GIB Definition
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