Instant BookMark .
[F11] [F12]
At any time, when you depress [F11], the current writing Position is saved in an internal Variable. Once this position is saved, you may move where you want in your Source. Then depressing [F12] will restore the Position saved by [F11]. Once back to this recorded Position, if you don't move and just depress [F12] again, the Editor will get back to the Position where you first ran [F12], enabling you with quick On-Off moves.
This feature is 'One Shot' (you can save only one given Position, like a single record BookMark), and it has no relationship with any of the other Source displacements features.
~~~~~~~