Constrains the rotation values of a selected object to another object without changing the location of the constrained object. A rotation performed on the constraining object is also performed on the constrained object.
For more information, see Orientation (Rotation) Constraints [ Animation ].
To apply: Select an object, Constrain 
Orientation, then pick the object to which the selected object will be constrained.
To redisplay: Select the constrained object, choose Explore Constraints on the MCP, and click the constraint's icon.
