3GPP 23.501 v20.2.0 — the document's own text
5.9.7 Internal-Group Identifier
Taught in 7. Every name the system uses (The 5G system architecture, in depth), 4. Knowing who you are and where you are (The 5G system architecture, overview).
The subscription data for an UE in UDR may associate the subscriber with groups. A group is identified by an Internal-Group Identifier.
NOTE 1: A UE can belong to a limited number of groups, the exact number is defined in stage 3 specifications.
NOTE 2: In this Release of the specification, the support of groups is only defined in non-roaming case.
The Internal-Group Identifier(s) corresponding to an UE are provided by the UDM to the SMF as part Session Management Subscription data and (when PCC applies to a PDU Session) by the SMF to the PCF. The SMF may use this information to apply local policies and to store this information in CDR. The PCF may use this information to enforce AF requests as described in clause 5.6.7.
The Internal-Group Identifier(s) corresponding to an UE are provided by the UDM to the AMF as part of Access and Mobility Subscription data. The AMF may use this information to apply local policies (such as Group specific NAS level congestion control defined in clause 5.19.7.5).