UIC Leaflet 736 gives a set of generic and specific requirements for signalling relays. This leaflet introduces a set of recommended requirements for signalling relay characteristics, construction, magnetic system, contacts and insulation. Requirements are coordinated with present international standards on all-or-nothing relays. Relays with the characteristics described in this leaflet are also known, outside railway signalling technology, as "relays with forcible guided (linked) contacts" (safety relays).