A web-resident, and persistent, proxy application for the mobile client is required to make this possible. This proxy acts as a device transformer for messages and embedded data flowing between the service and the mobile client. The interface between the mobile client and the on-web proxy is not within the scope of this International Standard and is covered by International Standards written by and within ISO/TC 204. This conceptual architecture is shown in Figure 32. In that diagram, thin and medium client nodes appear at the top of the diagram. The other nodes on the network are persistent, on-web services available to mobile clients through their “Proxy Application and Device Transformer”. Services specifically defined in this International Standard are marked as such. Other services in Figure 32 are examples, but may represent functionality required for the marked service. For example, “Gazetteer Service” should be compliant with ISO 19112.