Optional_Optional_Usage depends on the channel type
Optional_MIME type to send, or omit for no payload
Optional_rest-hook | websocket | email | sms | message
OptionalendpointWhere the channel points to
OptionalextensionAdditional content defined by implementations
OptionalheaderUsage depends on the channel type
OptionalidUnique id for inter-element referencing
OptionalmodifierExtensions that cannot be ignored even if unrecognized
OptionalpayloadMIME type to send, or omit for no payload
rest-hook | websocket | email | sms | message
Where the channel points to