Constraints, dimensions, and parameters are all used to create relationships that control, or constrain, Sketcher geometry. Geometry is constrained by the removal of degrees of freedom from the sketch. For example, if you apply a perpendicular constraint to two lines, you remove the angular degree of freedom between those lines. If you drag one of the lines, the other line must also move to maintain the perpendicular constraint.

If geometry is controlled such that you cannot change it without redefining the relationships—changing constraints, dimensions, or parameters—the geometry is fully constrained. Abaqus/CAE colors fully constrained geometry green to indicate that it cannot be changed. If you add too many constraints to a sketch, the geometry becomes overconstrained. Abaqus/CAE colors conflicting constraints magenta to indicate the overconstraint condition. To resolve an overconstraint, you can

• undo the last modification or constraint addition,

• delete constraints or dimensions, or

• convert unnecessary dimensions to reference dimensions.

If you intend to fully constrain an entire sketch, you can use the Detail query to list sketch information—including the number of unconstrained degrees of freedom—in the message area. For more information, see “Using the Query toolset in the Sketcher,” Section 20.4.8.

For information on related topics, click any of the following items:

• “Constraining, dimensioning, and parameterizing a sketch,” Section 20.12

• “Editing dimensions,” Section 20.13

• “Modifying objects,” Section 20.17

• “Undoing and redoing sketching actions,” Section 20.20