when you first enter 'short pulse mode' by hitting mode you are in 'set speed.' Then you press set again and you're in 'set frequency.' By pressing set one more time you enter 'saved wave.' If you were to hold set (rather than press set) this second time, you'd save a new wave rather than recall an older wave.
It operates exactly how it is displayed on the sticker adhered to the bottom of a Gen2 driver. If you have a Gen1 driver which has been updated, you may not have this sticker.
-Tim