the origin of operational data referring to one single responsibility. References to a data system are useful in an interoperated computer system

NOTE For SIRI, this entails in particular specific systems for assigning unique identifiers to relevant entities such as STOP POINTS or JOURNEYS, about which messages are to be exchanged, and which can be matched to the locally known entities identified by the respective internal operating data. The DATA SYSTEM must be mutually agreed between CLIENT and SERVER. A DATA SYSTEM has both a data model to describe the entities and their relationships, and a Namespace to describe the unambiguous set of identifier values.