V2X services. 13.6 Network Slicing for V2X 13.6 Network Slicing for V2X Network slicing has gained momentum as a prominent technology to flexibly support the diverse and even conflicting demands of 5G use cases that can run on top of a common phys- ical infrastructure, as described in [2]. It enables a new paradigm for flexible multi-tenancy among MNOs/infrastructure providers and mobile virtual network operators (MVNOs). A network slice is intended as a composition of adequately configured NFs, network applications, specific radio access settings, and underlying computing resources bundled together to meet the requirements of a specific use case. Slices are expected to be built in order to meet the demands of three reference service cat- egories identified by the International Telecommunication Union (ITU): enhanced mobile broadband (eMBB), which encompasses all the applications that require very high through- put to ensure access to multimedia contents, services, and data, such as ultrahigh definition video streaming and AR/VR; massive machine type communications (mMTC) (a.k.a. mas- sive IoT, mIoT), which include the non-delay-sensitive traffic generated by massively con- nected constrained devices; ultra-reliable and low-latency communications (URLLC), which are extremely sensitive to latency and require high reliability, such as emergency services and tactile Internet (ITU-R Rec. M2083, 2015). Owing to the peculiarities of their requirements, V2X services cannot be mapped into the reference slices for the aforementioned ITU service categories (see Ref. [3] and 3GPP TR 23.786, 2019). Besides the proper mapping into service slice, the V2X ecosystem also raises daunting challenges to conveniently engineer the slicing design. Such issues moti- vated specific 3GPP amendments and encouraged literature works, which will be reviewed in the Sections 13.6.1 and 13.6.2. 13.6.1 3GPP Specifications In order to meet the requirements of a specific slice, the relevant traffic needs to be prop- erly marked, identified, and tr