Section: 5.2.2.2.1 SIB validity
Content: The UE shall apply the SI acquisition procedure as defined in clause 5.2.2.3 upon cell selection (e.g. upon power on), cell-reselection, return from out of coverage, after reconfiguration with sync completion, after entering the network from another RAT, upon receiving an indication that the system information has changed, upon receiving a PWS notification, upon receiving request (e.g., a positioning request) from upper layers; and whenever the UE does not have a valid version of a stored SIB or posSIB or a valid version of a requested SIB. When the UE acquires a MIB or a SIB1 or an SI message in a serving cell as described in clause 5.2.2.3, and if the UE stores the acquired SIB, then the UE shall store the associated areaScope, if present, the first PLMN-Identity in the PLMN-IdentityInfoList for non-NPN-only cells or the first NPN identity (SNPN identity in case of SNPN, or PNI-NPN identity in case of PNI-NPN) in the NPN-IdentityInfoList for NPN-only cells, the cellIdentity, the systemInformationAreaID, if present, and the valueTag, if present, as indicated in the si-SchedulingInfo for the SIB. If the UE stores the acquired posSIB, then the UE shall store the associated areaScope, if present, the cellIdentity, the systemInformationAreaID, if present, the valueTag, if provided in assistanceDataSIB-Element, and the expirationTime if provided in assistanceDataSIB-Element. The UE may use a valid stored version of the SI except MIB, SIB1, SIB6, SIB7 or SIB8 e.g. after cell re-selection, upon return from out of coverage or after the reception of SI change indication. The valueTag and expirationTime for posSIB is optionally provided in assistanceDataSIB-Element, as specified in TS 37.355[ LTE Positioning Protocol (LPP) ]  [49]. A L2 U2N Remote UE in RRC_IDLE or RRC_INACTIVE can inform the interested SIB(s) to the connected L2 U2N Relay UE as defined in clause 5.8.9.8.2 and receive the SIB(s) from the L2 U2N Relay UE as defined in clause 5.8.9.9.3. A L2 U2N Remote UE in RRC_CONNECTED receives SIB1 and other SIB(s) in RRCReconfiguration message and performs on-demand SI request if required, as defined in clause 5.2.2.3.5 and 5.2.2.3.6. The L2 U2N Remote UE in RRC_IDLE or RRC_INACTIVE or RRC_CONNECTED is not required to obtain SI over Uu interface, but it may decide to perform the SI acquisition procedure over Uu interface as defined in clause 5.2.2.3 by UE implementation. NOTE: The storage and management of the stored SIBs in addition to the SIBs valid for the current serving cell is left to UE implementation. The UE shall: 1> delete any stored version of a SIB after 3 hours from the moment it was successfully confirmed as valid; 1> for each stored version of a SIB: 2> if the areaScope is associated and its value for the stored version of the SIB is the same as the value received in the si-SchedulingInfo for that SIB from the serving cell: 3> if the UE is NPN capable and the cell is an NPN-only cell: 4> if the first NPN identity included in the NPN-IdentityInfoList, the systemInformationAreaID and the valueTag that are included in the si-SchedulingInfo for the SIB received from the serving cell are identical to the NPN identity, the systemInformationAreaID and the valueTag associated with the stored version of that SIB: 5> consider the stored SIB as valid for the cell; 3> else if the first PLMN-Identity included in the PLMN-IdentityInfoList, the systemInformationAreaID and the valueTag that are included in the si-SchedulingInfo for the SIB received from the serving cell are identical to the PLMN-Identity, the systemInformationAreaID and the valueTag associated with the stored version of that SIB: 4> consider the stored SIB as valid for the cell; 2> if the areaScope is not present for the stored version of the SIB and the areaScope value is not included in the si-SchedulingInfo for that SIB from the serving cell: 3> if the UE is NPN capable and the cell is an NPN-only cell: 4> if the first NPN identity in the NPN-IdentityInfoList, the cellIdentity and valueTag that are included in the si-SchedulingInfo for the SIB received from the serving cell are identical to the NPN identity, the cellIdentity and the valueTag associated with the stored version of that SIB: 5> consider the stored SIB as valid for the cell; 3> else if the first PLMN-Identity in the PLMN-IdentityInfoList, the cellIdentity and valueTag that are included in the si-SchedulingInfo for the SIB received from the serving cell are identical to the PLMN-Identity, the cellIdentity and the valueTag associated with the stored version of that SIB: 4> consider the stored SIB as valid for the cell; 1> for each stored version of a posSIB: 2> if the areaScope is associated and its value for the stored version of the posSIB is the same as the value received in the posSIB-MappingInfo for that posSIB from the serving cell and the systemInformationAreaID included in the si-SchedulingInfo is identical to the systemInformationAreaID associated with the stored version of that posSIB: 3> if the valueTag (see TS 37.355[ LTE Positioning Protocol (LPP) ]  [49]) for the posSIB received from the serving cell is identical to the valueTag associated with the stored version of that posSIB; or if the expirationTime (see TS 37.355[ LTE Positioning Protocol (LPP) ]  [49]) associated with the stored posSIB has not been expired: 4> consider the stored posSIB as valid for the cell; 2> if the areaScope is not present for the stored version of the posSIB and the areaScope value is not included in the posSIB-MappingInfo for that posSIB from the serving cell and the cellIdentity for the posSIB received from the serving cell is identical to the cellIdentity associated with the stored version of that posSIB: 3> if the valueTag (see TS 37.355[ LTE Positioning Protocol (LPP) ]  [49]) for the posSIB received from the serving cell is identical to the valueTag associated with the stored version of that posSIB; or if the expirationTime (see TS 37.355[ LTE Positioning Protocol (LPP) ]  [49]) associated with the stored posSIB has not been expired: 4> consider the stored posSIB as valid for the cell;