PGC Edit's 'Toggle PGC playback breakpoint' option - what is it?

I looked through the documentation but it revealed nothing… Am I correct in saying that ‘Toggle PGC playback breakpoint’ under the ‘Trace’ menu would be used to select where the DVD would start from in powering the player off then on or stopped then started again, as opposed the ‘Toggle PGC pre/post breakpoint’ option which determines where the DVD starts when actually inserted into the player?