in a certain geo- graphic area the provisioning service of RAN is directly consumed by the local SON com- ponent, while in another area the deployment will include concentrators (entity B) between the RAN nodes and centralized SON function(s). Figure 6.5.3 The concept of exposure of network management services. Entity C The network management service X is consumed The network management service X is produced (exposed) Entity B The network management service X is consumed The network management service X is produced Entity A 6 Enabling Technologies In the service-based management architecture framework, a management function (MnF) is an MnS consumer, but may also play the role of MnS provider. For example, in Figure 6.5.3, entity A is an NF producing the MnS; entity B is MnF playing both roles (MnS provider and MnS consumer)s; and entity C is an MnS consumer. 6.5.4 NG-RAN and 5GC Information Models 3GPP information models for 5G, also called NRMs, 8 are specified in 3GPP TS 28.541. The NRM specification methodology includes separation of Stage 2 and Stage 3 standards, where Stage 2 specifies the semantics ("Information Service") while Stage 3 ("Solution Sets") specifies the syntax such as encoding used for information exchange between the MnS provider and MnS consumer. Protocol-independent Stage 3 definition decouples the NRM from the communication protocols. For example, an XML solution set can be used to support web service and NETCONF protocols, while a YANG solution set is not necessarily coupled with the NETCONF protocol. The following 5G NRMs are defined in 3GPP TS 28.541: NR NRM (3GPP TS 28.541, clause 4) 5GC NRM (3GPP TS 28.541, clause 5) Network slicing NRM (3GPP TS 28.541, clause 6), which includes the information models of NSI and NSSI. Examples of NRM elements described in the present section include basic elements of the RAN NRM "RRM policy." An NRM can be used with any of the following solution sets: XML-based 3GPP NR and NG-RAN NRM solution set (3GPP TS 28.541, annex C); JSON-based 3GPP NR and NG-RA