Re-read the spec. mate. He IS covering the properties as sparkytim says above. There is a standalone system within the flat, to 5839-6 (smokie in `principal habitable room`{adjacent to bedroom doors}, and heat alarm in kitchen). Then there is the heat detector from the communal system, inside the flat door leading onto the escape route. So, if the escape route is likely to be compromised due to a fire, ALL flats are sounded. If there is a minor mishap, which sets of 1 flat`s *optical* (for example), it won`t cause a full evac. UNLESS the heat alarm by the escape door is triggered.Does that make more sense?
KME