DIAMETR is CADKEY shorthand for diameter. DIAMETR lets you 
dimension the diameter of a specified arc or circle.

Choose an option for dimensioning the diameter:

REGULAR - lets you dimension the diameter of a circle or
          arc that appears in the same view as the one in
          which you are dimensioning.

EDGE    - lets you dimension an arc or circle that was
          created in a view that is different than the one
          in which you are dimensioning.
