Page "Compact Cassette" Paragraph 28

Some Compact cassettes were made to play a continuous loop of tape without stopping.

Lengths available are from around 30 seconds to a standard full length.

They are used in situations where a short message or musical jingle is to be played, either continuously or whenever a device is triggered, or whenever continuous recording or playing is needed.

Some include a sensing foil on the tape to allow tape players to re-cue.

From as early as 1969 various patents have been issued, covering such uses as uni-directional, bi-directional, and compatibility with auto-shut-off and anti-tape-eating mechanisms.