car OEMs, and their suppliers to implement intelligent transportation system (ITS) services in an interop- erable way, across different access networks, owned and managed by different MNOs and vendors (GSS+18). It is important to mention that among the plethora of standards developed by ETSI MEC, the API standards mentioned above are arguably the most important ones. That is because these standards define interfaces toward applications which are likely to be developed by a third party and therefore having a standardized API is crucial to ensure interoperability. Below we use the Location API standard (MEC013) as an example to illustrate the details of ETSI MEC APIs. 6.4.3.3 Location API The purpose of the MEC Location API is to allow the MEC platform and the authorized MEC applications to access a UE location. With this information, it is possible to track a 6.4 Multi-Access Edge Computing API client Location Service 1. GET: request to get UE Location 2. Response: UE Location API client Location Service Figure 6.4.3 UE location lookup procedure (Source: Reproduced with permission from © ETSI). UE, provide location-specific services, etc. Furthermore, the service supports anonymous (i.e. without a UE identification) location statistics collection. A MEC application can access location information using either: Location lookup procedures, i.e. "one-shot" location information request; or Location subscription procedures, which can provide periodic location information reporting to subscribed MEC applications. The UE location lookup procedure is illustrated by Figure 6.4.3. 1. When a MEC application needs a UE location, it sends the "request to get UE Location" information message to the Location Service for one or multiple UEs (identified e.g. by IP address). 2. The Location Service responds with a "UE Location" message, carrying the requested location information of the UE(s). Alternatively, if a MEC application is interested in receiving periodic UE location reports, it may use the UE location subscribe procedure,