Transponder 04 : A multiplex alarm transmission system at a protected site that is capable of receiving interrogation signals and supplying response signals of the status of the encoding devices connected to it
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}