Autodesk AUTOCAD 2006, Command Reference Manual, Page: 363 / 1490

If you select a line or an arc, the line or arc endpoints are used as the origins
of the extension lines. The extension lines are offset from the endpoints by
the distance you specify in Offset from Origin in the Lines and Arrows tab of
the New, Modify, and Override Dimension Style dialog boxes. See DIMSTYLE.
This value is stored in the DIMEXO system variable.
object selected dimension line
location designated
offset from origin
(DIMEXO system
variable)
If you select a circle, the diameter endpoints are used as the origins of the
extension line. When the point used to select the circle is close to the north
or south quadrant point, a horizontal dimension is drawn. When the point
used to select the circle is close to the east or west quadrant point, a vertical
dimension is drawn.
DIMORDINATE
Creates ordinate point dimensions
Dimension toolbar:
Viewpoint Presets Dialog Box | 339