Fairly self-explanatory. Basically, I have some objects that give off a one time particle effect on request, and they are timed quite tightly (lag can spoil the effect a bit). It occurred to me that calling llParticleSystem() with a huge list of parameteres for a one time effect is a bit wasteful, especially if it is repeated.
llResetParticleSystem() would tell clients to start an object's particle parameters from the beginning again, thus allowing simple repeating effects to be done without passing the whole parameter set around all the time. Could also be used to reset a slowly building up, but persistent effect (e.g one where particles have long life, but come in small bursts) for consistent effects.
Similar functions could be used for things like lights and flexible paths, allowing them to be simply toggled on/off. Only problem with that is that flexible and light settings don't appear to persist between being switched on and off, unless you save them in your script.
But for default lights being able to switch on/off would be neat and less wasteful. Though that might be better done with llSetStatus(STATUS_POINT_LIGHT, TRUE);