Hand-1
Hand-2
Hand-3
Hand-4
According to these hands,2♠ as a limited raise,we can be easier to find the meanings of the impossible 2♠ GIB played is 3 card ♠ with stopper in ♠,so there are many different with the impossible 2♠ re-bid most of us played.
For me,the exact meanings of that is ♠ 0-3 card without exact stopper in ♠.
so I suggest that GIB should tell us wether or not stopper in ♠.