strange, then maybe it means SET (active) PAUSE ON / OFF
EDIT : I guess SET PAUSE ON / OFF is little different from TOGGLE ACTIVE PAUSE, but I could be wrong; at least it reacts little differently when I press the different buttons in sim… but the general outcome of that two could be the same 
but found something here
Note : There are two work-arounds if you wish to freeze time as well as other aspects of the sim:
a) Use the Pause Simulation option in the Dev drop-down menu. It freezes time, including in the sim.
(Thanks to @AZRedneck33 in this post )…