G08B—SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
G08B5/00—Visible signalling systems, e.g. visible personal calling systems or remote indication of seats occupied
G08B5/22—Visible signalling systems, e.g. visible personal calling systems or remote indication of seats occupied using electric transmission; using electromagnetic transmission
G08B5/36—Visible signalling systems, e.g. visible personal calling systems or remote indication of seats occupied using electric transmission; using electromagnetic transmission using visible light sources