Various systems are available for the technical and operational
implementation of a River Information Service as specified in
the Guidelines and Recommendations for River Information
Services (RIS Guidelines): The electronic systems used to
communicate messages for inland navigation have recently come to
be referred to as RIS technologies. The systems that will
probably continue to be the most important for implementing RIS
are Key RIS technologies play a crucial role in those River
Information Services which are currently made available. The key
RIS technologies are: Efficient and effective use of the key RIS
technologies relies on the specification, codification,
formalisation and harmonised use of reference data. The most
important reference data are the vessel data and the RIS Index.
The data for identifying a vessel (hull data) are listed in
annex P of the Rhine Vessel Inspection Regulations (RVIR).
Article 2.18 of the RVIR specifies how the vessel data are to be
generated and used. The central component