This British Standard specifies performance requirements and test methods for a thief-resistant mechanically operated single-point lock assembly (including locking plates, fixing screws, fitting instructions, cylinders and protective furniture, where appropriate) that: incorporates a lock conforming to BSEN12209:2016 that, under normal conditions, can be unlocked from the inside without the use of a key, thereby allowing keyless egress; can be changed to a secure (no egress) mode by a secondary positive locking action; and is used in doors, window doors and entrance doors in buildings. This standard covers only those thief-resistant lock assemblies that are intended for use in dwellings where there is an alternative escape route. It does not cover thief-resistant lock assemblies that provide keyless egress at all times since these are covered by BS8621 , nor does it cover thief-resistant lock assemblies that require the use of a removable key for egress since these are covered by BS3621 . NOTE It is possible that lock assemblies conforming to this standard might not be suitable for use on doors constructed from certain types of material, e.g. plastic or aluminium. See Clause 9 , which specifies the information to be provided on the marking on the packaging of the lock assembly.