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.

Select the arc or circle to dimension.

Indicate the dimension text placement using an option
from the Position Menu.

If you place the text outside the arc or circle, choose 
the side of the dimension text you want the leader line
drawn from:

LEFT draws a leader from the left side of the dimension 
text; RIGHT draws a leader from the right side of the
dimension text.

CADKEY dimensions the diameter and prefixes the dimension
text with the ANSI-standard diameter symbol, 0. CADKEY
draws leader lines, dimension text, and arrows according
to the current settings under DETAIL, SET.

If you make a mistake, choose UNDO in the Break Area or
press (Alt)-(I). CADKEY deletes the dimension and leader 
lines and you can indicate another dimension text 
position.
