Hold on there Wonk!! The "action flats" as you call them are still the reference surface for the faces of the fence and the barrel flats. One hasn't done a good job of putting a gun back on face until the "action flats" are parallel with barrel flats. Since the action flats are commonly used as a reference to align other surfaces it makes water table a good name for that surface and one I prefer to use.

You and yours are well I hope.