• Position—A curve is said to be position constrained if the end of the curve is constrained to a point on another curve. A circle represents the Position constraint.

• Tangent Dependent—If you select a Tangent Dependent constraint when aligning two curves, the first curve that you select is modified while the second curve becomes the reference curve. The Tangent Dependent constraint sets the tangent at the end of the modified curve to match the tangency of the reference curve. Tangent Dependent curve constraint follows the concept of leaders and followers. When the shape of a leader curve changes, the follower curve adapts its shape to maintain the tangent connection. When the shape of a follower curve changes, the leader curve remains unaffected. An arrow pointing from the leader curve to the follower curve represents the Tangent Dependent constraint.

• Tangent Symmetric—Same as a Tangent Dependent but a change that you make to one curve does not affect another curve. The curves do not follow the concept of leaders and followers. A line between the curves represents a Tangent Symmetric constraint.

• Curvature Dependent—If you select Curvature Dependent constraint when aligning two curves, the first curve that you select is modified while the second curve becomes the reference curve. The Curvature Dependent constraint sets the curvature at the end of the modified curve to match the curvature of the reference curve. Curvature Dependent curve constraint follows the concept of leaders and followers. When the shape of a leader curve changes, the follower curve adapts its shape to maintain the curvature connection. When the shape of a follower curve changes, the leader curve remains unaffected. Two arrows pointing from the leader curve to the follower curve represent a Curvature Dependent constraint.