Improved-definition television

Improved-definition television (IDTV): Television transmitters and receivers that (a) are built to satisfy performance requirements over and above those required by the NTSC standard and (b) remain within the general parameters of NTSC standard emissions.

Note 1: IDTV improvements may be made at the TV transmitter or the receiver.

Note 2: Examples of improvements include enhancements in encoding, digital filtering, scan interpolation, interlaced line scanning, and ghost cancellation.

Note 3: IDTV improvements must allow the TV signal to be transmitted and received in the standard 4:3 aspect ratio. Synonym enhanced-quality television.

Source: from Federal Standard 1037C