e, carries the following information: gNB-DU ID gNB-DU Name A list of gNB-DU served cells, with their information gNB-DU RRC version. The gNB-DU ID and gNB-DU Name are used by the receiving gNB-CU to identify the sending NG-RAN network node (the Name IE is needed mainly for the purpose of human identification). The gNB-DU RRC version is used to prevent interoperability issues in case a gNB-DU and gNB-CU use different versions of the RRC specification. Every entry in the list of served cells contains the identifiers of a cell, for example, NR Physical Cell Identity (PCI), a list of served PLMNs (to support RAN sharing between multiple operators), and cell frequency and bandwidth information. This information can be used by a gNB-CU, for example, in decisions related to UE mobility (e.g. handover). Additionally, the message car- ries the gNB-DU System Information, that is Master Information Block (MIB) and System Information Block 1 (SIB1). Even though the gNB-DU is responsible for generating MIB and SIB1 parts of the overall system information, this information has to be available in the gNB-CU as well, in case the system information is provided to a UE in dedicated RRC signaling (as opposed to broadcast). The F1 Setup Response message, which is sent back to a gNB-DU in the case of successful F1 interface establishment, carries the following information: gNB-CU Name A list of cells to be activated gNB-CU RRC version. 4.2 High-Level gNB-CU/DU Split The gNB-CU Name and the RRC version IEs serve the same purpose as in the initiating message (see above). The list of cells to be activated has multiple purposes: To enable a gNB-CU to activate only some cells that a gNB-DU supports (e.g. for energy saving reasons); To indicate a list of PLMNs, which is needed for network sharing deployments; To carry the SI per cell that is generated by a CU (for the case when SI is delivered to a UE using broadcast signaling). All the F1AP interface maintenance-related messages are specified in 3GPP TS 38.473, clause 9.2.1, and the deta