To Create a Radial-Path Planar Curve
1. Click Style > Curve. The Curve tab opens.
2. To create a planar curve, click .
3. Click the References tab, click the Reference collector, and then click anywhere on the parent curve to construct a soft-plane at that point.
 The soft-plane is normal to the parent curve at the selected point. It displays a grid that is similar to the grid of the active datum plane.
4. On the soft-plane, click to create points that define the radial-path planar curve.
5. Click the References tab, and then select a radial plane type in the Type box.
Length Ratio—Sets the position of the soft-plane as a percentage of the length from the start of the parent curve to the soft-plane, relative to the total length of the parent curve.
Length—Sets the position of the soft-plane as the distance from the start of the parent curve to the soft-plane.
Parameter—Maintains the position of the soft-plane by keeping its parameter constant along the curve.
Offset from Plane—Sets the position of the soft-plane by intersecting the parent curve with a plane at a specific offset. Select a datum plane.
 If multiple intersections are found, the value parametrically closest to the previous value is used.
Lock to Point—Locks the soft-plane at a defining point on the parent curve, finding the closest defining point on the parent curve, typically an endpoint.
 The radial plane type sets the position of the soft-plane, and specifies how the soft-plane position updates during regeneration.
6. Type a value for the corresponding radial plane type in the Value box.
7. To export the value for modification outside Style, select the Value check box.
8. Closed curves are created as periodic. To change the closed curve to nonperiodic, click . Click again to change the curve back to periodic.
 For periodic curves, the value for the curve degree must be an odd number. When a curve of an even-numbered degree is changed to periodic, the degree increases by one.
9. To maintain the curve shape during edits by moving the free points in proportion to the soft points, click the Options tab, and select the Proportional Update check box.
 A curve without proportional update only changes shape at the soft point during edits.
10. Click .