Ray,
If you stop a run before the end,(I always pause then stop as Jeff said) you'll need to scroll to the last block executed (or any number of blocks (lines) before) and select "run from here"
mach will do some preparation moves (take care here !!) and then the run will continue.
If you press pause without then pressing stop, the tool will stop on the tool path and then continue along its merry way after you press start again.
If you press pause, stop, the axis movement stops as well as the spindle, if you press start again, Mach will obay the gcode as written but as there is no M03 spindle start instruction, mach will try cutting without the spindle running.
You migt be able to manually start the spindle (F5) or by clicking the spindle on icon, then press run Start and away you go.
I always use the run from here method.
ATB
Derek
So should it be allowed to restart after pressing program stop and make a B line to the look ahead point and run from there like nothing happened.
Ray.