A. This network function stores or retrieves subscriptions, profiles and authentication data to or from the data repositories. It offers services to the AMF, SMF, NEF and AUSF using the Service Based Interface.

B. This network function is part of data repositories in the Common Data Layer. It stores 3GPP standardized data.

C. This network function provides registration and discovery functionality to enable other network functions/services to discover and communicate with each other.

D. This network function is part of data repositories in the Common Data Layer and in opposition to the UDR, it stores non-standardized - unstructured - data.