First point

It creates a spline using points you specify, using NURBS (non-uniform rational B-splines) mathematics.

Specify  next points: Specify a point

Enter points until the spline curve will be defined. After entering two points, the following prompt will be displayed:

Specify next points or [Close] : Specify a point, enter an option, or press ENTER

Next point

Continuing to enter points adds additional spline curve segments until ENTER is pressed.After ENTER is pressed,a prompt will ask to specify the starting tangent for the spline curve.

Close

It closes the spline curve by defining the last point as co-incident with the first point and making it tangent to the joining point.

Start and End tangent

After pressing ENTER it will be possible to define the tangents to the starting and ending points of the Spline.

Starting tangent: it defines the tangent to the starting and ending points of the spline curve.

Specify tangent to the first point: Specify a point or press ENTER

The Specify Start Tangent prompt specifies the tangency of the spline curve at the first point.

Specify endpoint tangent: : Specify a point or press ENTER

The Specify End Tangent prompt specifies the tangency of the spline curve at the last point.

Or press ENTER to calculate the default tangents.