R

reference count

A control for a Component Object Model (COM) object. When an object is created, its reference count is set to 1. Every time an interface is bound to the object, its reference count is incremented; when the interface connection is destroyed, the reference count is decremented. The object is destroyed when the reference count reaches 0. All interfaces to that object are then invalid.

region

In DLS, a range of notes for which a particular digital sample is used in synthesizing an instrument's timbre.

root frame

A frame in Microsoft® Direct3D® that has no parent frame; it is at the top of a hierarchy of frames. The root frame contains the entire set of objects that make up a scene. See also scene.

RPN

Registered parameter number. Registered parameters have been assigned a function by the MIDI Manufacturers Association and can be accessed through controllers. For more information, see the MIDI specification.