## 4 Discussion
Critically, _guidelines for selecting and training remote operators_ could be interpolated from these requirements. This is highly relevant to rolling out highly automated vehicles since the role of having a Technical Supervisor to remotely monitor AVs and intervene, if necessary, i.e., a remote operator, was put forward as a requirement for SAE Level Four driving operations by several legislators on the German and European level [11; 38]. Thus, remote operation is likely to be an inevitable prerequisite for highly automated driving. Finally, the collection of scenarios may also be of importance for _mobility research in adjacent disciplines_. For instance, it could contribute to IT mobility services that require a holistic user-centered view on future mobility systems, embedded in a network of various means of transport, and feed data into a comprehensive mobility data space that is used to exchange mobility data. This is currently examined by the project \"GAIA-X 4 ROMS\" that aims at supporting and remote-operating automated and networked mobility services [39]. In spite of its numerous benefits, the catalogue of scenarios comes with certain limitations. Particularly, it must be noted that the catalogue does not claim to be exhaustive in several regards. First, not all the interactions between the actors proposed are addressed in the catalogue. Second, not every use case cluster or use case is considered at the same level of depth and detail which affects the balance of scenarios across use case clusters and use cases. The focus of this catalogue is on the projects and contexts that have been presented initially in this paper. Filling the gaps of the presented framework and coming up with more use case clusters, use cases, and scenarios is a quest for further research and inevitably depends on the context of use, the vehicles investigated, and their level of automation, as well as on the mode of remote operation and its concrete conceptualization. Also, categorizing the scenarios' consequences, e.g., by severity or impact, is left to future empirical investigations. Appropriate categorization systematics may be part of prospective iterations of this scenario catalogue, which is considered a living document that is permanently updated as research progresses. The same is true for deriving required measures for each scenario. Third, the categories used for analyzing the scenarios might not be mutually exclusive in certain cases. For instance, the listed consequences of some of the scenarios may already contain required measures even though deriving measures will be the subsequent step in the user-centered design process. This is because for comprehending these scenarios, indicating the required measures is inherently necessary. Moreover, only if the scenario is understood correctly, adequate design solutions can be derived from it. Further research is needed to evaluate and modify the categories used in this framework, if necessary, as well as to disentangle remaining underities in the categories assigned. At any rate, the remote operation of vehicles is likely to become a vital element of highly automated driving systems. Analyzing typical scenarios that may occur when remotely operating highly automated vehicles is a first but essential step towards enabling remote operation while designing with human needs at the center of attention. While the presented scenarios focus on the notion of controlling one vehicle at a time, feasible remote-operation solutions may need to be able to supervise several vehicles simultaneously. Also, communication of the remote operator with other road users is a research area that has not been investigated yet to the knowledge of the authors. Relying on external HMI solutions for highly automated vehicles (e.g., [40; 41]) may be a feasible approach. All in all, the presented catalogue of scenarios is an important milestone for bringing highly automated vehicles onto the roads as it is a precursor for testing and validating them under realistic conditions.