A point where a live performance must stop completely. This can be because of a large safety danger to the performers or the audience, a catastrophic failure of show systems (i.e. total power outage), or any of the many other terrible situations the mind can imagine. Depending on what caused the all stop and how soon/if the show can go on there are many different ways to handle an all stop. The thread about the lighting grid starting to fall talks about an example of an all stop.