Approved Locks

What do we mean by "approved door and window locks" fitted? All accessible windows have key operated locks (a). The main entrance door, any sliding patio doors or any other external doors are fitted with either: A wooden door with a five lever mortice deadlock (b) or A wooden door with a lock approved to the British Standard BS3621 (c) or A wooden door with a cylinder rim deadlatych with a key-locking handle on the inside or UPVC doors with multi point locking (d). If any sliding patio doors do not have one of the three options above, they need to have key operated patio-door lock mounted inside on the centre railes (e). If any external doors do not have one of the three options above they need to have key operated security devices fitted to the top and bottom in addition to existing locks (f).