And if not, it’s always in the source code In this case adv3/travel.t.
Overriding makeStandingUp() and dobjFor(GetOutOf) (the check() routine) should do it. They should exit the action when appropriate, and simply call inherited() when leaving should be allowed.
Ah, that’s the method I was looking for: makeStandingUp(). I had dobjFor(GetOutOf) working but could only stop the explicit STAND UP command by using the standUp() method in the PC’s object, but I really like having functional code in one spot – and this does the trick.