http://hl7.org/fhir/StructureDefinition/capabilitystatement-websocket|5.2.0

Where the server provides its web socket end-point. Note: this extension is deprecated because it's poorly defined and is also over-constrained to just 1 occurrence. If there is a need for an extension like this as a common extension, please submit a change request and we will create one that is better defined, clear about its purpose, and has an appropriate cardinality.