The Continua Design Guidelines (CDG) defines a framework of underlying standards and criteria that ensure the interoperability of devices and data used for personal connected health services. It also contains design guidelines (DGs) that further clarify the underlying standards or specifications by reducing options or by adding missing features to improve interoperability. This specification defines the additional design guidelines for the Authenticated Persistent Session (APS), whose function is to provide a secure, long-lived, persistent bidirectional data channel between the health and fitness services application and a PHG application, suitable for sending unsolicited commands to the PHG or to devices connected via the PHG. Recommendation ITU-T H.812.4 is part of the "ITU-T H.810 interoperability design guidelines for personal connected health systems" subseries that covers the following areas: - ITU-T H.810 - Interoperability design guidelines for personal connected health systems: System overview - ITU-T H.811 - Interoperability design guidelines for personal connected health systems: Personal health devices interface design guidelines - ITU-T H.812 - Interoperability design guidelines for personal connected health systems: Services interface design guidelines - ITU-T H.812.1 - Interoperability design guidelines for personal connected health systems: Services interface: Observation upload capability - ITU-T H.812.2 - Interoperability design guidelines for personal connected health systems: Services interface: Questionnaires capability - ITU-T H.812.3 - Interoperability design guidelines for personal connected health systems: Services interface: Capability exchange capability - ITU-T H.812.4 - Interoperability design guidelines for personal connected health systems: Services interface: Authenticated Persistent Session capability - ITU-T H.813 - Interoperability design guidelines for personal connected health systems: Healthcare information system interface design guidelines