Controls elements and keypoints so they cannot be modified during certain operations. A keypoint that has a lock relationship applied cannot be modified during operations that require a recompute such as changing the dimension value or dragging it to a new location. However, these keypoints can be moved by manipulation commands and will be fixed at the new location after manipulation.

When you add a lock relationship (A) to a keypoint, the elements that meet at the keypoint cannot be modified using that keypoint, but are free to move at their other keypoints. When you add a lock relationship to an element (B), the entire element cannot be modified.