RTZ
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Contents
CIRM's role
CIRM hosts the RTZ XML schema on the CIRM website, in accordance with IEC 61174:2015. The address of the hosted file is http://cirm.org/rtz.
NOTE: IEC 61174 Annex S refers to the RTZ namespace as http://cirm.org/RTZ/1/0. This has led to individuals interpeting this as a web URI, and trying to access the CIRM-hosted RTZ schema at this address. This is not a URI, but a namespace, which is used to link a route plan file with the schema when the XML code of the route plan file is checked. W3C writes all names to look like URLs, which causes confusion. These namespaces are unique identifiers, not links, and they are not referenced by the parser. When CIRM was setting this up we established that the requirements for using the namespace were that CIRM owned the domain and that we did not use it for any other purpose. The requirement was not to use the /RTZ/1/0 file path – it was sufficient to host the files at the path http://cirm.org/rtz.
Overview
Introduction
The route plan exchange format is specified in IEC 61174:2015 Annex S and is intended be used for many purposes. For example it can be used onboard for route plan exchange between main and backup ECDIS, ECDIS and radar, ECDIS and optimization systems, etc. Another example use is between ship and shore where it can be used to inform the shore about the plan of the vessel, the shore can recommend a route, the shore can optimize a route, etc.
The route plan exchange format is based on standardizing a single route plan. The application level of the sender and receiver is assumed to be able to handle multiple route plans for use cases which require availability of multiple routes, for example alternative route plans for the same voyage or route plans for different purposes.
A route plan consists of waypoints. Each waypoint contains information related to the leg from the previous waypoint. The route exchange format is a file containing an XML coded version of the route plan. The XML route exchange file uses the extension .rtz.
RTP Data container
Data containers are standard ZIP archive files used to compress the size of the route exchange files.
The container file .rtzp stores a XML file .rtz, which conforms to the XML schema. Use of the data container is optional with removable media. In this case the route exchange may be used with or without the data container. When used without the data container the filename of the route exchange is .rtz instead of .rtzp.
In addition to the .rtz file a number of free-format files may be placed in the data container. The semantic data link between the XML nodes and files may be documented using a HTTP like scheme "rtz://<URI>", where "<URI>" identifies a file name inside the data container.
High-level description of the RTZ format
The logical design of a route consists of three independent units:
- a block with general information about the route;
- a block with route geography (geometry) information which consists of blocks describing individual legs. Legs are listed in the order they appear on the route;
- a block that contains a set of route schedules.
Each block can be extended by manufacturers to fit their needs.
Adaptation to third-party extensions
Extended information in most cases refers to the geography (geometry) of a route. There is a possibility to keep extensions from different manufacturers in a single file.
Modifying the geography (geometry) of a route does not result in the data bindings in extensions becoming invalid; and when changing, adding or removing legs, data consistency does not break down due to unknown extensions in codes for a particular manufacturer.
Unique identification of a waypoint
Each waypoint in a route has a unique composite ID. It is assumed that all RTZ extensions use this identifier to link their data to the geography. The identifier consists of two parts: id, which allows the finding of a waypoint in the list; revision, which allows the determination of modifications of a waypoint since the entry of the data into a file extension.
Detailed RTZ format description
File components
The RTZ file consists of:
- the mandatory XML processing instruction, which allows the specification of the encoding of string data;
- a root <route> node, which includes the URIs of the standard namespace http://www.w3.org/2001/XMLSchema-instance as well as the RTZ namespace http://www.cirm.org/RTZ/1/0;
- the version attribute in the format "Major.Minor" (currently "1.0").
Route node description
This is the only "root" element of the RTZ file. It has one mandatory attribute "version" that contains the version of the RTZ format used during file creation.
Version is specified as a combination of two figures separated with a dot. The first figure corresponds to the major version. It shall be changed in the case of significant modifications to the document structure. Formats with different major versions are incompatible. The second figure corresponds to the minor version and indicates format changes that do not affect compatibility.
The Route node consists of a sequence of the following child nodes:
- RouteInfo node that contains basic information on the route;
- Waypoints node that describes the geographical components of the route;
- Schedules node that describes calculated schedule and timing defined by a user;
- Extensions node that allows for extending the format to fit the particular needs of a manufacturer.
