Thanks Kerry. I get it now. FWIW, in my non-analog capacity I
shoot a lot of stitched panoramas so the importance of a level
platform is understood.  When I asked earlier about it going
under a tripod head, I was alluding to mounting either a panning
base or a ball head with an incorporated panning base to the
leveling head.  Are the ballheads' balls marked in any way so
that the neutral, vertical position can be found quickly?