For example, coming down the glide path with only one engine turning...limited flaps/gear down...and, you decide to go around (for whatever reason)...you had to get the gear and flaps/slats up, and accelerate to about 200 KIAS (as you continue down the glide path). Once you got clean and 200 KIAS, you would be able to climb.
Same with the L-1011, however the required speed was 210...with a 'reasonable' weight (mass, for you European folks.)
I have done this several times in the aeroplane, when the sim was not available for PC's...works as advertised.
This was a superb confidence maneuver for First Officers as well, although it was not a required (graded) requirement, for them.