Constrains the diameter of a circle, an arc or an polyline arc segment. (This command is equivalent to the Diameter option of the DIMCONSTRAINT command.)
Accessing the Command
command bar: dcdiameter
menu bar: Parametric  2D Constraints  Diameter
ribbon: Parametric  2D Constraints  Radius  Diameter
toolbar: 2D Constraints 
: dcdiameter
Prompts you in the command bar:
Select arc, circle or curved polyline segment: (Select a circle, arc or polyline arc segment)
Specify dimension location: (Select a point to position the dimension line)
Dimension text <xx.xx>: (Type a value, or else press Enter to accept the current value)
The diameter of the entity is now constrained, although the entity can still be moved, rotated, and so on.
Command Options
Option 
Description 
Select arc, circle or curved polyline segment 
Select one entity:

Specify dimension location  Pick a point to position the dimension line 
Dimension text 
Enter an option:

Procedures
Related Commands
Dimconstraint  applies a dimensional constraint to an entity or between constraint points on entities; converts associative dimensions to dynamic dimensions.
Geomconstraint  applies geometric relationships between entities and/or valid constraint points on entities.
DcAligned  constrains the distance between two points.
DcAngular  constrains the angle between two lines or linear polyline segments; the total angle of an arc or an arc polyline segment; or the angle between three points on entities.
DcConvert  converts an associative dimension to a dimensional constraint.
DcHorizontal  constrains the horizontal distance (Xdistance) between two points with respect to the current coordinate system.
DcLinear  constrains the horizontal distance (Xdistance) or vertical distance (Ydistance) between two points with respect to the current coordinate system.
DcRadius  constrains the radius of a circle or an arc.
DcVertical  constrains the vertical distance (Ydistance) between two points with respect to the current coordinate system.
ConstraintBar  controls the display of the constraint bar of entities.
DcDisplay  allows to set dimensional constraints to be displayed or hidden.
Delconstraint  removes all dimensional and geometrical constraints from an entity.
CleanUnusedVariables  purges variables not used in constraint expressions and not linked to dimensions.
Parameters  manages 2D dimensional constraint parameters and user variables in the current drawing.