Nonperiodic spline

A spline with defined endpoints. If a spline's begin point and end point coincide, the spline is closed.

Notification sink

In a Microsoft® Visual Basic® for Applications (VBA) program, a class that receives events fired by a particular kind of Microsoft® Visio® object. In a stand-alone Visual Basic, C, or C++ program, an object that receives the notification sent by a Visio Event object and that enables two-way communication between a stand-alone solution and a Visio instance.

Number-unit pair

An expression that includes a number and a corresponding dimension. For example, "1 cm" is a number-unit pair.

NURBS (Nonuniform rational B-spline)

A commonly used way to represent curves, such as those drawn by the Freeform tool, mathematically.