Darryl, as you know there has been some discussion on this board as to prism diopters vs degrees, which i have to admit is my favorite term. However assuming the aboslute truth is prism diopters and that one equals apx 1.75 in power, then the question seems to me, is in a practical sense, how would you measure one with what instrument, where it would show you 1.75 on some sort of scale. Every vertometer i have ever seen has been marked 1,2,3 etc. progressively on circular rings. Now if that stands for 1.75, fine and dandy, but what good does it do you from a practical standpoint?