Keypoints through which a spline is fit. At least two keypoints must be defined. If P1 = P, graphical picking is enabled and all remaining command fields are ignored (valid only in the GUI).

The following fields are used only if specified end slopes are desired; otherwise, zero curvature end slopes will be automatically calculated. The slope vector is parallel to a vector pointing from the origin of the active coordinate system (CSYS) to the position in space that XV, YV, ZV represents in that system.

Orientation point of an outward vector tangent to line at P1. Vector coordinate system has its origin at the keypoint. Coordinate interpretation corresponds to the active coordinate system type, that is, X is R for cylindrical, etc. Defaults to zero curvature slope.

Orientation point of an outward vector tangent to a line at P6 (or the last keypoint specified if fewer than six specified). Defaults to zero curvature slope.