Section: 13.4.2 SRB5
Content: SRB5 is supported in NR-DC, but not in EN-DC, NGEN-DC and NE-DC. The decision to establish SRB5 is taken by the SN, which provides the SRB5 configuration using an SN RRC message. SRB5 establishment and release can be done at Secondary Node Addition and Secondary Node Change. SRB5 reconfiguration can be done at Secondary Node Modification procedure. SRB5 is used to send RRC messages (i.e., MeasurementReportAppLayer message) including application layer measurement report information directly to the SN. SRB5 is modelled as one of the SRBs defined in TS 38.331[ NR; Radio Resource Control (RRC); Protocol specification ]  [4] and uses the NR-DCCH logical channel type. When the SCG is released, SRB5 is released.