Section: 28.5.2 Telescopic FQDN
Content: The FQDN of the NF services or the authority part of URIs in another PLMN, may be appended with the PLMN Network Domain of the request initiating PLMN, as the trailing part to form a Telescopic FQDN as specified in 3GPP TS 33.501[ Security architecture and procedures for 5G System ]  [124]. The Telescopic FQDN shall be constructed as follows: <Label representing FQDN from other PLMN>.<FQDN of the SEPP in the request initiating PLMN>, where: - FQDN from other PLMN is the FQDN of the other PLMN NF (for e.g. returned in the NF Discovery Response) or the authority part of URIs from other PLMN, which may be rewritten by the other PLMN SEPP for topology hiding. The request initiating PLMN SEPP shall replace the other PLMN FQDN with a label; NOTE 1: How a SEPP constructs the label to replace the other PLMN FQDN is implementation specific. The label replacement is required in order to avoid multiple subdomains in the FQDN since the SEPP presents wildcard certificates on behalf of the other PLMN and only single level subdomain is allowed in a wildcard certificate as per IETF RFC 2818 [127]. NOTE 2: FQDN from other PLMN includes the network domain of the other PLMN. - FQDN of the SEPP in the request initiating PLMN is the identifier of the SEPP in the request initaiting PLMN (e.g. VPLMN).