Figure 4.1.1 shows the high level view of the non-roaming architecture for ProSe that is defined in TS 23.303.
In this Figure, UE A and UE B have subscriptions from the same PLMN.
Figure 4.1.2 shows the high level view of non-roaming inter-PLMN architecture for ProSe defined in TS 23.303. In this figure, PLMN A is the HPLMN of UE A, and PLMN B is the HPLMN of UE B.
Figure 4.1.3 shows the high level view of the roaming architecture for ProSe as defined in TS 23.303. In this Figure, UE A uses a subscription of PLMN A and UE B uses a subscription of PLMN B; UE A is roaming in PLMN C while UE B is not roaming.