UTM zones - west edge, overlap, v.mkquads

[Jean M Messersmith]

Scott, Melissa has a book on map projections that talks a little about
the "overlap" issue. I can't remember the name but it is a government
document. The best I understand about the UTM overlap is that at  less than
~250000 E and greater than ~750000 E the overlap between the zones begins
(~25 mile overlap). "Theoretically" you should never be able to get to
zero because the distortion becomes too great. The 250000 might just be
a general approximation of the transition zone, but I should think you
should be able to go beyond that number a get closer to zero. Maybe
the computer program realizes when it gets too close to the border that
the distortion becomes too great. I should think there would be a way to
override that though. 

I hope that helped.
Jean