ConstReadonlyServiceRequest: EntityKindNameThe request side of a service, which takes the rq prefix and the Request suffix.
ReadonlyServiceResponse: EntityKindNameThe reply side of a service, which takes the rr prefix and the Reply suffix.
ReadonlyTopic: EntityKindNameA topic, which takes the rt prefix.
The ROS 2 subsystem a name belongs to, which fixes its DDS prefix and suffix.
Provided as a runtime object plus a matching string-union type.