BS 3621:2017 specifies performance requirements and test methods for a thief?resistantmechanically operated single-point lock assembly (including locking plates, fixing screws, fittinginstructions, cylinders and protective furniture where appropriate) that:

a) incorporates a lock conforming to BS EN 12209:2016 that can be locked from both sides with akey thereby only allowing key egress; and
b) is used in doors, window doors and entrance doors in buildings.

This standard does not cover thief-resistant lock assemblies that provide keyless egress, i.e. lockassemblies that can always be unlocked from the inside without the need for a key, or lock assembliesthat provide a secure (no egress) mode in addition to keyless egress.Cross References:BS EN 1303:2015PAS 24:2016BS EN 12209:2016BS 7398:1991 BS 10621:2007BS EN ISO/IEC 17065:2012BS 8621:2007305/2011/EUBuilding Regulations 2010Construction Products Regulations 2013