This specification states how a specific grouping of one or more maps from one or more map servers can be described in a portable, platform-independent format for storage in a repository or for transmission between clients. This description is known as a “Web Map Context Document,” or simply a “Context.” A Context document includes information about the server(s) providing layer(s) in the overall map, the bounding box and map projection shared by all the maps, sufficient operational metadata for Client software to reproduce the map, and ancillary metadata used to annotate or describe the maps and their provenance for the benefit of human viewers. A Context document is structured using eXtensible Markup Language (XML). If you are interested in a more powerful alternative that supports web services beyond WMS consider using OWS Context.
Request For Comment (RFC)
OGC Seeks Public Comment on Candidate OGC SensorThings API Extension: WebSub Asynchronous Messaging Standard