Do they just mean that the partnership must not stop below game under any circumstances or does it just mean that the partnership must not stop below 3NT but might in some circumstances settle for 4 in a minor? And is 'unequivocally game forcing" just the same thing but with added emphasis?
For example, in lebensohl the sequence 1NT (2♠) 3♥ is described (in my book anyway) as game forcing, but the choices for opener's next bid are to raise to game with three cards, or bid 3NT with a stopper, or find a better game.
If the bid is game forcing then only alternatives here seem to be to bid 3NT or 4♥. I assume opener has to bid regardless of any doubts he might have, and just accept it as one of those things?