To Change a Tangent's Directional Constraints
1. Open the Style feature that contains the curve you want to edit.
2. Select a curve and perform one of the following operations:
◦ Right-click and choose 
Edit Definition from the shortcut menu.
Edit Definition from the shortcut menu.◦ Click 
Style > 
Curve Edit.
Style > Curve Edit.The Curve Edit tab opens.
3. Select an endpoint to display the tangent vector for a curve with interpolation points. For curves with control points, select the control point nearest to the endpoint.
4. Perform one of the following operations:
◦ Right-click the tangent vector and choose a tangent constraint from the shortcut menu.
◦ Click the Tangent tab, and then select a constraint in the First or Second box.
5. On the Tangent tab, in the Drag box, select the way the tangent vector can be modified:
◦ Free—Does not constrain the tangent direction.
◦ Equal Length (Alt)—Applies the same length value to each active tangent when you drag multiple tangents.
◦ Angle + Elev (Alt + Ctrl)—Locks the length so that only the angle and elevation change.
◦ Length (Alt + Shift)—Locks the direction so that only the length changes.
 | The drag setting does not apply constraints to the selected tangent. |
6. Click 
.
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