Autodesk AUTOCAD 2006, Command Reference Manual, Page: 379 / 1490

To specify a user-defined arrowhead block, select User Arrow. The Select
Custom Arrow Block dialog box is displayed. Select the name of a
user-defined arrowhead block. (The block must be in the drawing.)
Arrow Size
Displays and sets the size of arrowheads. (DIMASZ system variable)
Center Marks
Controls the appearance of center marks and centerlines for diameter and
radial dimensions. The DIMCENTER, DIMDIAMETER, and DIMRADIUS
commands use center marks and centerlines. For DIMDIAMETER and
DIMRADIUS, the center mark is drawn only if you place the dimension line
outside the circle or arc.
None
Creates no center mark or centerline. The value is stored as 0 in the DIMCEN
system variable.
Mark
Creates a center mark. The size of the center mark is stored as a positive
value in the DIMCEN system variable.
Line
Creates a centerline. The size of the centerline is stored as a negative value
in the DIMCEN system variable.
Size
Displays and sets the size of the center mark or centerline. (DIMCEN system
variable)
Arc Length Symbol
Controls the display of the arc symbol in an arc length dimension. (There is
no system variable for this setting.)
Preceding Dimension Text
Places arc length symbols before the dimension text.
Above Dimension Text
Places arc length symbols above the dimension text.
New, Modify, and Override Dimension Style Dialog Boxes | 355