G PHYSICS
G08 SIGNALLING
G08B SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
21/00 Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
G08B21/02 Alarms for ensuring the safety of persons
G08B21/04 responsive to non-activity, e.g. of elderly persons
G08B21/0407 based on behaviour analysis
G08B21/0423 detecting deviation from an expected pattern of behaviour or schedule