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Descriptions of ITN attributes
Go to: Feature referencing attributes | Life cycle metadata | Other attributes | Supplementary data attributes
In OS MasterMap® Integrated Transport Network™ Layer (ITN), attribution provides additional information about a feature. This information could relate to the real-world object the feature represents, or it could relate to the properties of the feature itself. For example, the theme the feature belongs to is an attribute, as is the unique reference (TOID). The descriptive group is a property of the real-world object; the reference is a property of the OS MasterMap feature.
Some attributes are optional and some may occur multiple times in the same feature. FerryLink, for example, has a start and end node but no line feature because the ferry is not as constrained as to where it can go as it crosses water, unlike a vehicle passing along roads. Many attributes are common to all features, but some are specific to a particular feature type.
Feature referencing attributes
theme
A theme to which the feature belongs: Road Network, Road Routing Information (RRI) or Urban Paths Network.
TOID
The unique identifier consisting of a number and the four-letter prefix ‘osgb’. We recommend that the TOID is treated as a character rather than a number as some TOIDs have zeros at the beginning of the number element. The TOID should always be retained/stored in its entirety.
Life cycle metadata
version
The version number of the ITN feature, identifying that a feature has been altered. Version numbers will be allocated sequentially, with version 1 representing the creation of the feature.
versionDate
The date when this version of the feature became the current version. This is the date on which the feature was changed in the database; it is not the date when the real-world object it represents changed.
reasonForChange
The reason why a new version (or new feature) has been created or an existing feature changed. There may be more than one reason per version.
changeDate
The date of the reason for change. This date will not necessarily be the same as the version date; it is likely to be earlier as it records when the change was observed by a survey in the real world.
The reasonForChange and changeDate attributes are collectively known as the changeHistory attributes because they provide the reasons that led to this particular version of a feature coming into existence.
Other attributes
These attributes are not common to all feature types. Refer to the Road Network and Urban Paths attribution checklists to see which attributes belong to which features.
boundedBy
A minimum bounding rectangle covering all the RoadLink features referenced by a Road feature.
dateTimeQualifier
A date/time qualifier specifies the date and/or time period when the routing information applies. This may be known named dates/times such as ‘school hours’ or 'dusk to dawn', specified dates/times, a particular day (Sunday), specified dates range, a particular time or a specified time range.
descriptiveGroup
The classification of the feature, which will be one of the following: ‘Named Road’, ‘Motorway’, ‘A road’ or ‘B road’, ‘Named Path’, ‘Path’, ‘Path Routing Information’, ‘Ferry Connection’ or ‘Path Topology’.
If there is no name or number for the links, as sometimes occurs on roads or paths within estates, the links are included but no road name or path name feature is created.
descriptiveTerm
This provides further classification information about the feature.
directedLink on PathRouteInformation features and PathPartialRouteInformation features (Urban Paths Network only)
An ordered set of references to the PathLink features to which PathLink or PathRouteInformation applies.
directedLink on RoadRouteInformation features and RoadPartialRouteInformation features (Road Network only)
An ordered set of references to the RoadLink features to which RoadLink or RRI applies.
directedNode
The RoadNode or PathNode at the start or finish of a RoadLink or PathLink, or the FerryNode at the start or finish of a FerryLink. The start node has a negative direction and the end node a positive direction. A directed node could also be a reference to a FerryNode feature. The directed node on RoadLink or PathLink features also indicates the level of grade separation.
distanceFromStart
This attribute is the distance, from the start node, along a RoadLink or PathLink that an RRI feature or Path Routing Information (PRI) feature occurs.
environmentalQualifier
This attribute specifies any known environmental conditions useful for routing such as the existence of a ford or level crossing.
junctionName (Road Network only)
The distinctive name applied to a motorway road junction and the classified roads not included in the junction number that intersect with the motorway, such as M4 J16/A38 (currently, coverage is limited to numbered motorway junctions). On occasions, junctions have more than one name. Such junctions are described as follows: M4 J20/M5 J15.
length
The length of the RoadLink or PathLink, in metres, calculated from the planimetric coordinates making up the RoadLink or PathLink.
natureOfRoad (Road Network only)
Defines the type of road feature that a RoadLink represents, such as single or dual carriageway.
networkMember
A collection of RoadLink or PathLink features that make up this distinct road. This collection is an unordered set of features referenced by their TOID. This attribute is used to attach the RoadLink to the road name or number or to attach the PathLink to the path name.
pathName (Urban Paths Network only)
The distinctive name applied to the path, such as ‘Camden Passage’. Where Ordnance Survey has names in more than one language, such as Welsh or Gaelic, each name is represented.
point
A coordinate pair in the British National Grid reference frame.
polyline
A set of coordinate pairs in the British National Grid reference frame.
referenceToNetwork
References to RoadNode, PathNode and FerryNode features. The TOIDs of the node feature reference the appropriate road, path or ferry link feature.
referenceToNode
A reference to the TOID of the RoadNode or PathNode to which the RoadNode or PathNode information point relates.
referenceTo PathLink (Urban Paths Network only)
A reference to the PathLink to which the PathLinkInformation or PathPartialLinkInformation feature relates.
referenceToRoadLink (Road Network only)
A reference to the RoadLink to which the RoadLinkInformation or RoadPartialLinkInformation feature relates.
referenceToTopographicArea
The TOID or TOIDs of the topographic area road or path polygons from OS MasterMap Topography Layer that intersect with the RoadLink, PathLink, PathNode or RoadNode feature.
Where ITN links do not intersect topographic area road polygons, a default value of -9999 will be used.
roadName
The distinctive name or DfT number applied to the road, such as ‘Romsey Road’, ‘M25’, ‘A43’ and ‘B336’. Where Ordnance Survey has names in more than one language, such as Welsh or Gaelic, each name is represented
subsectionDistance
Where required, this provides the distances from the start of a link feature that an RRI or PRI feature begins and ends.
subsectionPoint
Where required, the National Grid eastings and northings of the start and end points of the routing information. These are coincident with vertices on the underlying RoadLink or PathLink.
vehicleQualifier
This attribute identifies the vehicles the information applies to by specifying the defining attributes of a vehicle, such as its use, size, weight and contents.
Supplementary data attributes- frozen dataset
Customers taking the RRI theme as well as the Road Network theme are supplied supplementary information on physical weight and width restrictions. This additional information is provided as a separate CSV file upon written request. Weight and width restrictions typically indicate real-world objects such as weak bridges, narrow bridges or ‘pinch points’ along a road where the carriageway narrows significantly. It is anticipated that this information will be of most use to commercial users of the road with larger vehicles, such as HGV drivers and haulage firms.
Another supplementary dataset, also available as a CSV file upon written request, provides information on steep and very steep gradients. Knowing the location of potential gradient problems helps commercial vehicles plan the most efficient route.
These attributes are not features in their own right and are not attributes of existing RRI features, although they may become so in the future. As a result, they do not have a TOID. They have grid coordinates that allow GIS application software to create and display the attributes against a point. These coordinates record a position on, or very near to, the relevant RoadLink feature. To reduce any possible ambiguity over which RoadLink feature the weight or width restriction applies to, the TOID of the RoadLink is supplied along with the road name and/or number.
Please note that from 1st January 2012 both of these datasets are frozen as the December 2009 supply.
In this section:
ITN Technical specification – home
ITN Road Routing Information (RRI) theme
ITN Path Routing Information (PRI) theme
Feature types and attribution in the Road Network theme
Feature types and attribution in the Road Routing Information theme
Feature types and attribution in the Urban Paths Network theme
Feature types and attribution in the Path Routing Information theme
Descriptions of ITN Layer attributes
Attribution checklists for the Road Network and Urban Paths Network themes
ITN attribute definitions and values
This web page is part of the technical specification for OS MasterMap® Integrated Transport Network™ Layer. For the terms that apply to use of this specification, refer to Purpose of this specification.