Extended-definition television

Extended-definition television (EDTV): Television in which (a) improvements are made to the standard National Television System Committee (NTSC) television system, (b) the improvements are receiver-compatible with the standard NTSC television system, and (c) the improvements modify the standard NTSC television system emission standards.

Note 1: EDTV improvements may include (a) a wider aspect ratio, (b) a higher picture definition than NTSC definition, and (c) any of the improvements used in improved-definition television (IDTV).

Note 2: When EDTV signals are transmitted in the 4:3 aspect ratio, it is referred to as "EDTV." When transmitted in a wider aspect ratio, it is referred to as "EDTV-Wide."

Source: from Federal Standard 1037C