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A code list is a controlled set of allowable labels or codes represented as an alphanumeric attribute. The pages in this section show the code lists used within OS VectorMap Local. Some of the code lists apply to attributes of multiple feature types, whereas others will only apply to attributes of one feature type.
The following OS-defined Functional Sites have been classified as Important Buildings in OS VectorMap Local:
Coastguard Lookout
Fire Service Training
Fire Station
Hospice
Hospital
Lifeboat Station
Police HQ
Police Services
Police Station
First School
Further Education
Higher Education
Infant School
Junior School
Middle School
Non-State Primary Or Preparatory School
Non-State Secondary School
Primary School
School
School For Special Needs
Secondary School
University
University College
Place Of Worship
Cathedral
Chapel
Church
Citadel
Gurdwara
Kingdom Hall
Minster
Mosque
Synagogue
Temple
Bus Station
Coach Station
Funicular Railway Station Or Stop
Passenger Ferry Terminal
Preserved Line Railway Station Or Stop
Principal Railway Station
Railway Station
Ship Passenger Terminal
Vehicular Ferry Terminal
Vehicular Ferry Terminal International
Vehicular Rail Terminal
Tram Station Or Stop
Underground Railway System Station
Aviation Museum
Industrial Museum
Maritime Museum
Military Museum
Museum
Science Museum
Transport Museum
Central Government Services
Customs Inspection
HM Detention Centre
HM Prison Service
Law Court
Local Government Services
Conference Or Exhibition Centre
Hostel
Library
Observatory
Post Office
Tourist Information
Youth Hostel
Attribution that defines text placement and appearance.
A number between 0 and 8 that specifies which part of the text is bound to the anchorPoint.
Type: AnchorPositionValue
Length: 1
Multiplicity: [1]
A value of 0, 1 or 4 that can be used as a basis for determining which font to use when displaying the text.
Type: TextFontValue
Length: 1
Multiplicity: [1]
The height of Text. The height is expressed as the distance on the ground covered by the text, in metres.
Type: Integer
Length: 3
Multiplicity: [1]
The orientation of text or symbol features for cartographic placement, and for text. Given in tenths of a degree anticlockwise from due east (0–3599).
Type: Angle
Length: 5
Multiplicity: [1]
OS VectorMap Local is supplied in GeoPackage format. GeoPackage (*.gpkg) is an open, non-proprietary, platform-independent, standards-based data format for geographic information systems (GIS), as defined by the Open Geospatial Consortium (OGC). It is designed to be a lightweight format that can contain large amounts of varied and complex data in a single, easy-to-distribute and ready-to-use file. GeoPackage is natively supported by numerous software applications. GeoPackage offers users the following benefits:
The single file is easy to transfer and offers the end-user a rich experience.
Attribute names are not limited in length, making the format user-friendly.
The file size limit is very large at 140 TB.*
It supports raster, vector and database formats, making it a highly versatile solution.
It is an OGC standard.
In most cases, it is a plug-and-play format.
For information on how to open, use and understand a GeoPackage dataset, please refer to our Getting Started with GeoPackage guide, which is available on the OS website. Further detailed information on GeoPackage can be taken from the GeoPackage website.
* A file size limit might be imposed by the file system to which the file is written.
GeoPackage outputs Booleans as integers, either ‘1’ or ‘0’, where ‘1’ = ‘true’ and ‘0’ = ‘false’. These data types are used on override, suppressed and inTunnel attributes for the RoadCLine Feature Type and on supressed and inTunnel attributes for the RailCLine Feature Type (see Figure 2). GML outputs Booleans as ‘true’ and ‘false’ values.
In instances where a particular feature class is not present in the GML, no tables will be created in the output GeoPackage. For example, some of the sparsely populated tiles may not contain a road or rail feature; in this case, the GeoPackage will be created without RoadCLine and / or RailCLine tables.
Features representing topographic objects and concepts that have a line-based geometry.
An ordered set of points forming a line feature.
Type: GM_Curve
Length: N/A
Multiplicity: [1]
A unique feature identification. IDs will be retained between iterations but will not be version controlled.
Type: CharacterString
Length: 38
Multiplicity: [1]
A unique feature code to facilitate analysis and styling.
Type: FeatureCodeValue
Length: 5
Multiplicity: [1]
A description of the feature code.
Type: FeatureDescriptionValue
Length: 60
Multiplicity: [1]
Line representing the estimated centre line of a road.
An ordered set of points forming a line feature.
Type: GM_Curve
Length: N/A
Multiplicity: [1]
A unique feature identification. IDs will be retained between iterations but will not be version controlled.
Type: CharacterString
Length: 38
Multiplicity: [1]
A unique feature code to facilitate analysis and styling.
Type: FeatureCodeValue
Length: 5
Multiplicity: [1]
A description of the feature code.
Type: FeatureDescriptionValue
Length: 60
Multiplicity: [1]
The number of the road defined by the Department for Transport.
Type: CharacterString
Length: 10
Multiplicity: [0..1]
The name of the road as reflected in local signage.
Type: CharacterString
Length: 100
Multiplicity: [0..1]
The drawLevel value of the Road, used for cartographic styling. The valid values are defined in the DrawLevelValue code list.
Type: DrawLevelValue
Length: 1
Multiplicity: [1]
The override value of the Road, used for cartographic styling.
Type: Boolean
Length: N/A
Multiplicity: [1]
The suppressed value of the Road, used for cartographic styling.
Type: Boolean
Length: N/A
Multiplicity: [1]
Determines whether the road alignment is in a tunnel and is used for cartographic styling.
Type: Boolean
Length: N/A
Multiplicity: [1]
Features representing topographic objects that have a polygon-based geometry.
A polygon is a single closed region defined by a set of lines that represent the boundaries.
Type: GM_Surface
Length: N/A
Multiplicity: [1]
A unique feature identification. IDs will be retained between iterations, but they will not be version controlled.
Type: CharacterString
Length: 38
Multiplicity: [1]
A unique feature code to facilitate analysis and styling.
Type: FeatureCodeValue
Length: 5
Multiplicity: [1]
A description of the feature code.
Type: FeatureDescriptionValue
Length: 60
Multiplicity: [1]
This technical specification provides detailed technical information about OS VectorMap Local. It is targeted at technical users and software developers.
OS VectorMap Local is a mapping dataset designed for providing contextual mapping output on paper, PCs, hand-held devices or the Internet. The vector format of the product consists of layers to enable you to customise and style the output to suit your needs.
The product is generated automatically from the OS Large-Scale Topographic Database with no manual cartographic input. This database is used to update other OS products, including OS MasterMap Topography Layer.
This Technical Specification contains detailed technical information about the data in both raster and vector formats. For basic information required to understand and use OS VectorMap Local, please refer to the Overview, which is available on the Product Support page on the OS website.
OS VectorMap Local raster data is supplied in GeoTIFF file format (Geographic Tagged Image File Format). The product is available in three raster formats: Full Colour, Backdrop and Black & White.
GeoTIFF LZW (Lempel Ziv Welch) is a TIFF file which has geographic (or cartographic) data embedded as tags within it. The geographic data can then be used to position the image in the correct location and with precise geometry on the screen of a geographic information display.
When an image is compressed, duplicated data that has no value is removed or saved in a shorter form, reducing a file’s size. For example, if large areas of water are the same tone, only the value for one pixel needs to be saved, together with the locations of the other pixels with the same colour. When the image is edited or displayed, the compression process is reversed. When raster data is compressed, not only are the data volumes reduced, but the user can download, display, edit and transfer images more quickly.
There are two forms of compression: lossless and lossy. OS VectorMap Local raster tiles are lossless compressed.
Lossless compression
As its name suggests, lossless compression does not lose information within an image. A lossless compression retains the original quality of an image when it is uncompressed. This process doesn’t provide much compression, so file sizes remain large. Lossless compression is used mainly where detail is important, such as when planning to make large prints.
GeoTIFF 8-bit LZW compressed
400 dots per inch (DPI)
GeoTIFF 1-bit LZW compressed
400 dots per inch (DPI)
OS VectorMap Local is available in three vector formats:
Geography Markup Language (GML) 3.2.1
GeoPackage
Vector tiles (MBTiles)
These file formats contain a set of features and identifiers which conform to the data structures outlined in the following sub-sections.
In OS VectorMap Local vector data for GML, vector tiles and GeoPackage formats, each feature is given a unique identifier: a featureID. The featureIDs are maintained between iterations. For GML only, this allows feature-level change-only updates (COUs) to be delivered. The COUs will consist of a selection of inserts and deletes related to real-world and generalisation generated change (see the GML overview section of this document for more information). Vector tiles and GeoPackage formats do not have a COU option.
The data structure is described below by means of unified modeling language (UML) class diagrams and accompanying tables containing text. The UML diagrams conform to the approach specified in the ISO 19103 Conceptual Schema.
Colour conventions have been used in the diagrams and tables to distinguish the properties that have been added in this specification. In the UML class diagrams, feature types in the Ordnance Survey product specification are coloured orange. The tables which follow in this Technical Specification use orange for a feature type, blue for a code list and purple for a data type.
The following stereotypes are used on UML elements:
GeoPackage overview
GML overview
Feature types
Code lists
Structured data types
Feature codes and descriptions
Vector tiles overview
Important Buildings classification
Features representing topographic objects and other concepts that have a point-based geometry.
A pair of easting and northing co-ordinates in metres, defining a horizontal location in the British National Grid spatial reference system.
Type: GM_Point
Length: N/A
Multiplicity: [1]
A unique feature identification. IDs will be retained between iterations but will not be version controlled.
Type: CharacterString
Length: 38
Multiplicity: [1]
A unique feature code to facilitate analysis and styling.
Type: FeatureCodeValue
Length: 5
Multiplicity: [1]
A description of the feature code.
Type: FeatureDescriptionValue
Length: 60
Multiplicity: [1]
The orientation of symbol features for cartographic placement. Given in tenths of a degree anticlockwise from due east (0–3599).
Type: Angle
Length: 4
Multiplicity: [1]
Line representing the estimated centre line of a rail.
An ordered set of points forming a line feature.
Type: GM_Curve
Length: N/A
Multiplicity: [1]
A unique feature identification. IDs will be retained between iterations but will not be version controlled.
Type: CharacterString
Length: 38
Multiplicity: [1]
A unique feature code to facilitate analysis and styling.
Type: FeatureCodeValue
Length: 5
Multiplicity: [1]
A description of the feature code.
Type: FeatureDescriptionValue
Length: 60
Multiplicity: [1]
The suppressed value of the Road, used for cartographic styling.
Type: Boolean
Length: N/A
Multiplicity: [1]
Determines whether the road alignment is in a tunnel and is used for cartographic styling.
Type: Boolean
Length: N/A
Multiplicity: [1]
The coordinate position that a piece of text is positioned relative to.
Type: GM_Point
Length: N/A
Multiplicity: [1]
A unique feature identification. IDs will be retained between iterations but will not be version controlled.
Type: CharacterString
Length: 38
Multiplicity: [1]
A unique feature code to facilitate analysis and styling.
Type: FeatureCodeValue
Length: 5
Multiplicity: [1]
A description of what the feature codes represent.
Type: FeatureDescriptionValue
Length: 60
Multiplicity: [1]
Provides the information to graphically display a text string in harmony with the underlying map detail and consists of anchorPosition, font, height and orientation.
Type: textRenderingType
Length: N/A
Multiplicity: [1]
Textual information that can be rendered using the textRendering attribute.
Type: CharacterString
Length: 150
Multiplicity: [1]
OS VectorMap Local is supplied as a national vector tiles set in a single MBTiles file (combined from individual PBF tiles). This is a lightweight set of tiles that are efficient and fast to render in supported software, provide high-resolution data and give a seamless experience when zooming in and out. The data is supplied in Web Mercator projection (EPSG:3857).
The vector tiles schema is detailed in the following table. In the zoom levels columns within the table, the letter N indicates that the specified layer and attribute is not mapped within that zoom level, whereas the letter Y indicates that the specified layer and attribute is mapped within that zoom level.
| Attribute | Zoom level: 0 to 8 | 9 | 10 | 11 | 12 | 13 | 14 |
|---|
| Attribute | Zoom level: 0 to 8 | 9 | 10 | 11 | 12 | 13 | 14 |
|---|
| Attribute | Zoom level: 0 to 8 | 9 | 10 | 11 | 12 | 13 | 14 |
|---|
| Code list: FeatureCodeValue | Code list: FeatureDescriptionValue | Notes (where applicable) |
|---|
This section describes the features which make up OS VectorMap Local. The attributes associated with these feature types are listed below along with a brief description of their data properties.
The name of the attribute and what it is describing.
The nature of the attribute, for example a numeric value or a code list value.
The length of the attribute provided (optional).
Describes how many times this element is expected to be populated in the data. An attribute may be optional or mandatory within the product. These are denoted by:
‘1’ – there must be a value.
‘0..1’ – population is optional but a maximum of one attribute will be returned These values may be used in combination.
| Stereotype | UML element | Description |
|---|---|---|
| Attribute | Zoom level: 0 to 8 | 9 | 10 | 11 | 12 | 13 | 14 |
|---|
| Attribute | Zoom level: 0 to 8 | 9 | 10 | 11 | 12 | 13 | 14 |
|---|
| Attribute | Zoom level: 0 to 8 | 9 | 10 | 11 | 12 | 13 | 14 |
|---|
FeatureType
Class
A spatial object type [ISO 19136].
Codelist
Class
A controlled set of values for a free text data type that may be extended.
DataType
Class
Structured data type.
0
The default draw level. Roads with draw level 0 are to be displayed first, with draw levels 1, 2 and 3 overlaid on top.
1
Used for road bridges and overpasses. Roads with draw level 1 are to be overlaid on top of draw level 0.
2
Used when there are several coincident levels of road bridge or overpass. Roads with draw level 2 are to be overlaid on top of draw levels 0 and 1.
3
Used when there are several coincident levels of road bridge or overpass. Roads with draw level 3 are to be overlaid on top of draw levels 0, 1 and 2.
feature_id | N | Y | Y | Y | Y | Y | Y |
feature_code | N | Y | Y | Y | Y | Y | Y |
feature_description | N | Y | Y | Y | Y | Y | Y |
feature_id | N | Y | Y | Y | Y | Y | Y |
feature_code | N | Y | Y | Y | Y | Y | Y |
feature_description | N | Y | Y | Y | Y | Y | Y |
feature_id | N | Y | Y | Y | Y | Y | Y |
feature_code | N | Y | Y | Y | Y | Y | Y |
feature_description | N | Y | Y | Y | Y | Y | Y |
orientation | N | Y | Y | Y | Y | Y | Y |
feature_id | N | Y | Y | Y | Y | Y | Y |
feature_code | N | Y | Y | Y | Y | Y | Y |
feature_description | N | Y | Y | Y | Y | Y | Y |
road_number | N | Y | Y | Y | Y | Y | Y |
road_name | N | Y | Y | Y | Y | Y | Y |
draw_level | N | Y | Y | Y | Y | Y | Y |
override | N | Y | Y | Y | Y | Y | Y |
suppressed | N | Y | Y | Y | Y | Y | Y |
in_tunnel | N | Y | Y | Y | Y | Y | Y |
feature_id | N | Y | Y | Y | Y | Y | Y |
feature_code | N | Y | Y | Y | Y | Y | Y |
feature_description | N | Y | Y | Y | Y | Y | Y |
suppressed | N | Y | Y | Y | Y | Y | Y |
in_tunnel | N | Y | Y | Y | Y | Y | Y |
feature_id | N | Y | Y | Y | Y | Y | Y |
featur_code | N | Y | Y | Y | Y | Y | Y |
feature_description | N | Y | Y | Y | Y | Y | Y |
text_rendering_anchor_position | N | Y | Y | Y | Y | Y | Y |
text_rendering_area | N | Y | Y | Y | Y | Y | Y |
text_rendering_height | N | Y | Y | Y | Y | Y | Y |
text_rendering_orientation | N | Y | Y | Y | Y | Y | Y |
text_string | N | Y | Y | Y | Y | Y | Y |
15010 | Building Outline | N/A |
15011 | Important Building Outline | Buildings defined as important by OS (see Annex A). |
15013 | Glasshouse Outline | N/A |
15017 | Building Name | N/A |
15014 | Building Polygon | Building polygons over 20m². |
15015 | Important Building Name | N/A |
15016 | Glasshouse Polygon | Glasshouse’s polygons over 50m². |
15030 | Urban Extent | An OS approximation of the extents of urban development. |
15031 | Urban General Line Detail | Real-world linear features, including fences, hedges, walls and other minor detail within OS urban areas. |
15032 | Rural General Line Detail | Real-world linear features, including fences, hedges, walls and other minor detail in rural areas. |
15033 | Urban General Pecked Detail | Tracks and paths and other non-obstructing features within urban areas. |
15044 | Rural General Pecked Detail | Tracks and paths and other non-obstructing features within rural areas. |
15100 | Tunnel Alignments | N/A |
15101 | Overhead Peck Detail | Overhead features that are not power lines, for example, aerial ropeways and ski lifts. |
15102 | Electricity Transmission Line | N/A |
15104 | Pylon | N/A |
15110 | Point Feature1 | Generic topographic features which are too small to be represented by an area feature, for example, posts, poles, masts, and wind turbines. |
15120 | Antiquity Site | N/A |
15121 | Antiquity Building Name | N/A |
15112 | Miscellaneous Name | Most generic text, including towns, cities, buildings and general areas names, for example, commons or woodland, etc. |
15122 | Antiquity Miscellaneous Name | N/A |
15200 | Parish Or Community Boundary | N/A |
15201 | District Or LB Boundary | N/A |
15202 | County, Region Or Island Boundary | N/A |
15203 | Parliamentary Boundary | N/A |
15210 | Boundary Text | N/A |
5211 | Boundary Point | N/A |
15300 | Multi Track Railway | N/A |
15302 | Narrow Gauge Railway | N/A |
15301 | Single Track Railway Or Siding | N/A |
15303 | Railway Bridge | N/A |
15304 | Footbridge | N/A |
15400 | Standard Contour Line | 5m vertical interval contour intervals. |
15401 | Index Contour Line | 25m vertical interval contour intervals. |
15403 | Index Contour Label | Index contour height value. |
15404 | Spot Height Label | N/A |
15405 | Spot Height Position | N/A |
15406 | Air Height Position | N/A |
15407 | Air Height Label | N/A |
15408 | Triangulation Station | N/A |
15409 | Standard Contour Label | Standard contour height value. |
15410 | Ridge Or Rock Line | N/A |
15442 | Refuse Or Slag Heap | N/A |
15500 | Coniferous Woodland | N/A |
15501 | Coniferous Woodland And Shrub | N/A |
15502 | Mixed Woodland | N/A |
15503 | Mixed Woodland And Shrub | N/A |
15504 | Broad-leafed Woodland | N/A |
15505 | Broad-leafed Woodland And Shrub | N/A |
15506 | Orchard | N/A |
15507 | Shrub | N/A |
15508 | Shrub And Heathland | N/A |
15509 | Shrub And Unimproved Grass | N/A |
15510 | Shrub And Unimproved Grass And Boulders | N/A |
15511 | Shrub And Marsh | N/A |
15512 | Shrub And Marsh And Heath | N/A |
15513 | Shrub And Marsh And Unimproved Grass | N/A |
15514 | Shrub And Heathland And Unimproved Grass | N/A |
15515 | Shrub And Heathland And Boulders | N/A |
15516 | Shrub And Boulders | N/A |
15517 | Heathland | N/A |
15518 | Heathland And Unimproved Grass | N/A |
15519 | Heathland And Unimproved Grass And Boulders | N/A |
15520 | Heathland And Boulders | N/A |
15521 | Heathland And Marsh | N/A |
15522 | Unimproved Grass | N/A |
15523 | Unimproved Grass And Boulders | N/A |
15524 | Unimproved Grass And Shingle | N/A |
15525 | Unimproved Grass And Sand | N/A |
15526 | Marsh | N/A |
15527 | Marsh And Unimproved Grass | N/A |
15528 | Reeds | N/A |
15529 | Inland Rock | N/A |
15530 | Boulders | N/A |
15531 | Boulders And Shingle | N/A |
15532 | Boulders And Sand | N/A |
15533 | Boulders And Mud | N/A |
15534 | Shingle | N/A |
15535 | Shingle And Sand | N/A |
15536 | Shingle And Mud | N/A |
15537 | Sand | N/A |
15538 | Mud | N/A |
15540 | Vegetation Or Landform Limit | N/A |
15550 | Custom Landform Polygon | A polygon to contain representations of rocks, cliffs, scree and extensive areas of slope. |
15560 | Top Of Standard Slopes | N/A |
15562 | Top Of Cliff | N/A |
15600 | Water Feature | N/A |
15601 | Aqueduct | N/A |
15603 | Water Name | N/A |
15604 | Mean High Water | N/A |
15605 | Mean Low Water | N/A |
15606 | Point Feature Water1 | Generic water features which are too small to be represented by an area feature, for example, wells, springs and collects. |
15608 | Sea Polygon | N/A |
15609 | Inland Water Polygon | Larger inland water bodies, for example, lakes and ponds. |
15610 | Standard Flow Arrow | Indicates direction of flow. |
15611 | Large Flow Arrow | Indicates direction of flow on larger water bodies. |
15701 | General Road Name | N/A |
15710 | Motorway, Alignment | N/A |
15711 | Motorway, Road Number | N/A |
15712 | Motorway, Road Name | N/A |
15720 | A Road, Trunk, Alignment | N/A |
15721 | A Road, Trunk, Road Name | N/A |
15722 | A Road, Trunk, Road Number | N/A |
15723 | A Road, Primary, Alignment | N/A |
15724 | A Road, Primary, Road Name | N/A |
15725 | A Road, Primary, Road Number | N/A |
15726 | A Road, Primary And Trunk, Alignment | N/A |
15727 | A Road, Primary And Trunk, Road Name | N/A |
15728 | A Road, Primary And Trunk, Road Number | N/A |
15729 | A Road, Alignment | N/A |
15730 | A Road, Road Name | N/A |
15731 | A Road, Road Number | N/A |
15740 | B Road, Primary, Alignment | N/A |
15741 | B Road, Primary, Road Name | N/A |
15742 | B Road, Primary, Road Number | N/A |
15743 | B Road, Alignment | N/A |
15744 | B Road, Road Name | N/A |
15745 | B Road, Road Number | N/A |
15750 | Minor Road, Alignment | N/A |
15751 | Minor Road, Road Name | N/A |
15760 | Local Road, Alignment | N/A |
15782 | Restricted Local Access Road, Alignment | N/A |
15761 | Local Road, Road Name | N/A |
15790 | Local Road, Shared Use Carriageway, Alignment | N/A |
15770 | Secondary Access Road, Alignment | N/A |
15791 | Local Road, Shared Use Carriageway, Road Name | N/A |
15771 | Secondary Access Road, Road Name | N/A |
15793 | Restricted Local Access Road, Guided Busway, Alignment | N/A |
15780 | Local Access Road, Alignment | N/A |
15794 | Restricted Local Access Road, Guided Busway, Road Name | N/A |
15781 | Local Access Road, Road Name | N/A |
15783 | Restricted Local Access Road, Road Name | N/A |
15795 | Enclosed Traffic Area, Alignment | Used to ensure road connectivity through enclosed traffic areas, for example, car parks. |
0 | Antiquity descriptions |
1 | Default |
2 | N/A (obsolete value that's no longer utilised in the Text Feature Type) |
3 | N/A (obsolete value that's no longer utilised in the Text Feature Type) |
4 | Detailed road names |
This section describes the structured data types which make up OS VectorMap Local. The attributes associated with these data types are listed below along with a brief description of their data properties.
The name of the attribute and what it is describing.
The nature of the attribute, for example a numeric value or a code list value.
The length of the attribute provided (optional).
Describes how many times this element is expected to be populated in the data. An attribute may be optional or mandatory within the product. These are denoted by:
‘1’ – there must be a value.
‘0..1’ – population is optional but a maximum of one attribute will be returned These values may be used in combination.
Geography Markup Language (GML) is an XML grammar for expressing geographic features. GML serves as a modeling language for geographic systems as well as an open interchange format for geographic transactions on the Internet. More information can be found on the Geography Markup Language Standards page on the Open Geospatial Consortium (OGC) website.
The XML specifications that GML is based on are available from the World Wide Web Consortium (W3C) website.
Information about Unicode and UTF-8, the character encoding we have chosen, is available on the Unicode Consortium website.
Feature attribute: A property of a feature implemented as an XML element, as defined in ISO 19109.
XML attribute: Attribute as used in an XML context is referred to as an XML attribute.
Property: Most feature attributes are encoded as GML properties – property means a GML property.
XML schemas are used to define and validate the format and content of the GML. The GML 3.2.1 specification provides a set of schemas that define the GML feature constructs and geometric types. These are designed to be used as a basis for building application-specific schemas, which define the data content.
The Ordnance Survey application schemas, which are referenced by the data, are available online. These schemas make use of XML schema definitions (XSDs) and document type definitions (DTDs) produced by the W3C, which are available from the W3C website.
The W3C-provided XSDs and DTDs are as follows:
xml.xsd: to allow the use of the xml:lang attribute for language qualification.
XMLSchema.dtd: Required by xml.xsd.
datatypes.dtd: Required by XMLSchema.dtd.
The OGC-provided schemas are:
feature.xsd: The feature and property constructs.
geometry.xsd: The geometric constructs, such as polygon and point.
xlinks.xsd: A schema based on the W3C XLINK recommendation provided by the OGC to make use of the XLINK constructs.
The Ordnance Survey-provided schema is as follows:
OSVectorMapLocal.xsd: The feature type, complex type, and simple type declarations.
The ‘OSVectorMapLocal’ schema document defines the following XML namespaces:
The location of the schema is defined as:
https://www.ordnancesurvey.co.uk/xml/cmdschema/local/V2/OSVectorMapLocal.xsd
GML is designed to support a wide variety of capabilities, ranging from simple contextual mapping, such as OS VectorMap Local, to products that include complex geometric property types or even spatial and temporal topology. The Simple Features Profile of GML 3.2.1 defines a restricted subset of GML, allowing scope for greater interoperability.
This product conforms to Simple Features Profile – Level 0.
A geometric property is one that describes a specific geometry. All geometric properties are encoded according to the Simple Features Profile, as referenced above.
The XML attribute ‘srsName’ shall be set to ‘urn:ogc:def:crs:EPSG::27700’, which uses eastings and
northings specified in metres.
EPSG (European Petroleum Survey Group) provides numeric identifiers for many common projections and associated projections or coordinate metadata (such as measurement units or central meridian) for each identifier.
OS VectorMap Local data is available in GML 3.2.1, the most up-to-date version of GML used by Ordnance Survey. This is a simplified single file schema. Code lists will be managed as Code list dictionaries, residing outside of the product schema. Enumerations have been removed.
GML 3.2.1 is supported by most software suppliers and can be read natively with multiple GIS packages without the need for a translator.
OS VectorMap Local will provide GML feature-level change-only updates (COUs). Only change features will be supplied, rather than all of the data within a tile that has changed within it. The product contains maintained feature-level identifiers to enable change to be detected between releases. These identifiers will not have version information.
The features within a COU file will be supplied as transactions. In the OS VectorMap Local product, a transaction identifies whether a feature is new or if it has been removed from the product. These two types of transaction are defined as follows:
<os:insert> These are features which have been newly inserted into the product or the customer’s area of interest (AOI) since the last product supply.
<os:delete> These are features which have ceased to exist in the last product release or features that have moved out of the customer’s AOI. Features which have been deleted will be supplied with the entire feature’s attribution. These features should be removed from the customer's live data holding.
Existing features which have undergone a generalisation, geometry or attribution change since the previous release will be managed in the following way: the feature that existed in the previous release will be entered as a deleted feature in the new COU release, and a new feature with a new ID will be added as an insert, replacing the deleted feature.
In order to maintain the topological relationships of features, the product will not ‘cut’ features at tile edges. This will remove the requirement to merge features which have been separated artificially at tile edges. Exceptions to this include contours, tidal limits (mean high and mean low water) and boundary features.
This will require holdings to be de-duplicated once all tiles have been loaded due to duplication of features which cross tile edges.
In order to remove legacy data and improve the analytical capability of the product, we have added an additional feature class, RailCLine. A number of feature codes have been added, while others have been removed.
The unified modeling language (UML) class diagram of OS VectorMap Local in GML format can be seen below. In the UML diagram, feature types from the Ordnance Survey product specification are orange, all code lists are coloured blue and data type is purple.
0 | Lower left text anchor position. |
1 | Middle left text anchor position. |
2 | Upper left text anchor position. |
3 | Lower middle text anchor position. |
4 | Centre text anchor position. |
5 | Upper middle text anchor position. |
6 | Lower right text anchor position. |
7 | Middle right text anchor position. |
8 | Upper right text anchor position. |
