Ciena Corporation Ciena Corporation Ciena Corporation Arrcus, Inc. Verizon RFC 9252 defines BGP signaling procedures for SRv6 services, including the use of an MPLS Label field and transposition semantics. However, when transposition is not used (i.e., TL = 0), RFC 9252 does not explicitly define the interpretation of the MPLS Label field, leading to ambiguity in control-plane signaling. This document specifies a minimal, backward-compatible extension to RFC 9252 that enables a single route to unambiguously advertise both a valid MPLS Service Label and an SRv6 Service SID. The extension relies on existing MPLS label semantics, without introducing new TLVs, attributes, or changes to the base encoding format.