In
telecommunication, a
viewdata is a type of
information-
retrieval service[?] in which a
subscriber can (a)
access a remote
database via a
common carrier channel, (b) request
data, and (c) receive requested data on a
video display over a separate channel.
Note: The access, request, and reception are usually via common carrier broadcast channels. Contrast with teletext.
Source: from Federal Standard 1037C