Introduction

The following pages provide an overview of the OS National Geographic Database (OS NGD); they cover the core elements of its design, including data formats, the coordinate reference systems used, and how Change-Only Updates (COUs) will be provided, amongst other topics:

• Terminology and access

• File formats and naming

• Data ordering and currency

• COU supplies

• Data schema versioning

• Unique identifiers

• Coordinate reference systems

• Attribute information for feature types

OS NGD data is different from our other products because you access it from a single source where you'll find the data you need without having to download unnecessary datasets. It also has a simple data structure, designed to help you quickly answer questions and develop more intelligent solutions.

OS NGD terminology: themes, collections and feature types

Theme

A theme is a macro grouping of features which all represent similar geographic entities. Themes are the highest level of grouping within the OS NGD, and examples include ‘Buildings’ and ‘Transport’.

Themes allow for quick discovery and navigation when using OS Select+Build (the OS NGD download service) or the OS NGD APIs. They also give you the ability to quickly access all OS data relating to your particular theme of interest.

The nine OS NGD themes are: , , , , , , , , and .

Collection

A collection is a sub-grouping of the OS NGD themes. Collections group together similar types of data within a theme. Examples include ensuring network and routing data is separated from topographic features. For example, in the OS NGD Water Theme, there are two collections: OS NGD Water Features (topographic data) and OS NGD Water Network (network data).

This makes it easier for you to access only the data you require.

Feature type

A feature type is the most granular level of grouping within the OS NGD. Feature types have their own data model and specifications which are not commonly shared with other feature types.

When you order data through OS Select+Build (the OS NGD download service), the data you receive will be provided at a feature type level.

Who can access the OS NGD?

How do you access the OS NGD?

The OS NGD is available via the on either the . There are three access methods to choose from once you are on the OS Data Hub:

• OS Select+Build: A download service which enables you to choose only the data you require and select how you want to receive your data.

• OS NGD API – Features: An OGC API – Features service.

• OS NGD API – Tiles: A vector tiles service based on OGC API – Tiles.

OS Select+Build

The GeoPackage and CSV formats accessible via OS Select+Build are available in four different coordinate reference systems dependent on your selection:

• British National Grid (BNG: EPSG: 27700)

• British National Grid + ODN Height (EPSG: 7405)

• European Terrestrial Reference System (ETRS89: EPSG: 4258)

• World Geodetic System (WGS84: EPSG: 4326)

Default coordinate reference systems for OS Select+Build

The following table outlines the default coordinate reference system used by each OS NGD collection in OS Select+Build:

Selecting a coordinate reference system

When creating a new data package in OS Select+Build (the Download service for OS NGD), you can choose what coordinate reference system you'd like to receive the data in.

If you don't choose a particular coordinate reference system for your data package, OS Select+Build will automatically select the default coordinate reference systems for the feature types in your data package for you.

OS NGD APIs

OS NGD API – Features

The GeoJSON format accessible via OS NGD API – Features is available in four different coordinate reference systems:

• British National Grid (BNG: EPSG: 27700).

• World Geodetic System (WGS84: EPSG: 4326)

• British National Grid + ODN Height (EPSG: 7405)

• Web Mercator (EPSG: 3857)

OS NGD API – Tiles

The vector tiles format accessible via OS NGD API – Tiles is available in two different coordinate reference systems:

• British National Grid (BNG: EPSG: 27700)

• Web Mercator (EPSG: 3857)

Definitions for the coordinate reference systems available in the OS NGD

On the feature type pages (which are located in the Data Structure section), the following information can be found about each attribute:

• Name and Definition: The name of the attribute and what it is describing.

• Data Types: The values the attribute can take. For example, a numeric value or a string. This is provided for all three data formats – GeoJSON, GeoPackage, and CSV.

• Nullable: A True or False value to denote whether the attribute always has to be populated with a value (False) or can be NULL (True).

• Code List Name: The name of the code list used in association with the attribute (if applicable) and a hyperlink to the page displaying that code list.

• Max Length: Values are given here to indicate the maximum length that you will find in the attribute, to aid in developing applications.

• Multiplicity: Describes how many times this value is expected to be populated in the data. These values may be used in combination.

  • 1: There must be a value.

  • 2: There must be two values.

  • n: There may be one or more values.

  • 0: Population is optional.

• OS NGD API – Features Filterable: A Yes / No value to denote whether you can refine your query in OS NGD API – Features specifically on this attribute.

• OS Select+Build Filterable: A Yes / No value to denote whether you can refine your order in OS Select+Build on this attribute.

• Data Schema Version: The OS NGD schema version the data above applies to. Please note that concurrent schema versions may be available at one time. For more information on how data schema versioning works in the OS NGD, please refer to the Data schema versioning page.

Change-Only Updates (COUs) are only available for CSV data supplies of the OS NGD. The benefit of taking COU supplies is that you only receive the features which have changed since your last supply, reducing the overall size of the files you receive.

There are some restrictions on when you can choose to take COUs; these restrictions are dependent on the selections you make when ordering OS NGD data. Please see the 'Data ordering and currency' page for more information.

Upon OS NGD launch, if you choose to receive a COU supply for your CSV data, this can be provided on either a daily or monthly frequency. In both cases, your COU file will contain any changes which have been made to the underlying data within the selected time frequency. If no changes have been made to a selected feature type of your choice, then you will receive a blank COU file.

The key attribution required to use and implement a COU is detailed below:

• Unique Identifier: The unique identifier for the feature type you are using is how you will ensure you are updating the correct records in your data holdings. In most instances the unique identifier will be the OSID, but this is not always true, therefore please check the appropriate feature type pages in our documentation.

• Version Date: This is the date when the feature was last updated in OS product databases.

• Version Available From Date: This is the date when the feature became the latest version and was published to customers.

• Version Available To Date: This is the date when the feature was superseded by an update or ceased to exist.

• Change Type: This is a code list which gives more information about the type of change which has occurred.

Primary unique identifier for the OS NGD

The OS NGD primarily uses a new identifier called the OSID (OS Identifier) to uniquely identify features. The OSID is used persistently and allows the unique identification of records in the OS NGD. It should be noted that the OSID is not unique across the OS NGD but rather is only unique at a feature type level. The reason for this is, when possible, the same OSID will be used on multiple features when they represent the same geographical feature. For example, a point feature in the OS NGD Geographical Names Theme which represents a water body will have the same OSID as the more detailed water body representation in the OS NGD Water Theme.

Other unique identifiers

UPRN, USRN and UDPRN

Other unique identifiers are also present in the OS NGD, including the UPRN (Unique Property Reference Number), USRN (Unique Street Reference Number) and UDPRN (Unique Delivery Point Reference Number); these remain the unique identifiers in our data to represent Local Authority Address, Local Authority Street and Royal Mail delivery point address records, respectively. (A UDPRN is a unique and persistent identifier that Royal Mail assigns to identify a specific delivery point, for example, a mailbox or business unit.)

TOID

The Topographic Identifier (TOID) is also present in the OS NGD, but in most instances, this is an optional attribute and therefore should not be relied upon to complete data linking or for implementing COUs (Change-Only Updates). The reason for this identifier being optional is the improved currency on which the OS NGD will be published, meaning the TOID which is created in our existing OS product systems will not always be allocated to features as frequently as they will be accessible via the OS NGD.

Available formats for OS NGD data

OS NGD data is available in four easy-to-use formats: GeoPackage, CSV (comma-separated values), GeoJSON and vector tiles. The download service of OS Select+Build supports GeoPackage and CSV. OS NGD API – Features supports GeoJSON. OS NGD API – Tiles supports vector tiles.

CSV overview

CSV files are delimited text files which use commas to separate each attribute from the next. CSV is one of the file formats available via OS Select+Build. A single record is commonly provided per line, with a new line being started for each new record.

Geometry attribution will be provided as Well-Known Text (WKT).

CSV offers the following benefits:

• The single file is familiar to many customers and well used across GIS and data science tools.

• It is plug and play with most databases.

• The ability to quickly load large datasets using COPY method rather than INSERT.

CSV structure

The following table shows how different attribute types in the OS NGD are delivered when you choose to receive a CSV format. This includes whether to expect quotes, and how NULL values are treated.

GeoPackage overview

GeoPackage (GPKG) is an open standard data format as defined by the Open Geospatial Consortium (OGC). It is one of the file formats available via OS Select+Build. GeoPackage 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. Please be advised that older versions of GIS software may need updating before being able to display and interact with GeoPackage files.

GeoPackage offers 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 it user-friendly.

• The file size limit is very large at 140TB, so lots of data can be easily accommodated (please note that a file size limit may be imposed by the file system to which the file is written).

• 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.

GeoJSON overview

GeoJSON is an IETF standard designed to represent simple geographical features and their non-spatial attributes. It is used for encoding geographic data structures using JavaScript Object Notation (JSON). GeoJSON is used by OS NGD API – Features.

More information about the GeoJSON IETF standard can be found here.

Supported geometry types:

• Point

• LineString

• Polygon

• Multipart geometries: MultiPoints, MultiLineString, or MultiPolygon features

Vector tiles overview

Vector tiles are clipped tiles, or grid squares, composed of layers of vector features which are optimised for caching, scaling and producing map imagery quickly. They serve in a similar way to raster tiles but have the added functionality of being customisable by users. A client application requests tiles based on a zoom level and extent, and the server responds with binary data representing the vector tiles containing the layers to be visualised on that map.

OS NGD API – Tiles serves vector tiles as raw information which is presented using compressed packets of geographic data using the Protocolbuffer Binary Format (.pbf).

Vector tiles offer the following benefits:

• User customisation and styling functionality – customise your map with full and dynamic design control.

• Small file size – lightweight tiles that are efficient and quick to render in your client application.

• Pixel perfect maps – high-resolution, beautiful mapping for all devices (web and mobile devices).

• Snapping ability – due to the data being vector, data can be snapped to and traced.

• Smooth zooming and scaling effect – a seamless user experience when zooming in and out of maps.

• Advanced features – vector tiles contain geographic data (not just images) which can be interrogated and analysed.

File naming

When you place an order for OS NGD data via OS Select+Build, the following file naming convention will be applied to the data you receive:

themeshortcode_collectionshortcode_featuretype

In order to keep file names manageable and not overly long, shortened file names ('short codes') have been used for both the theme and collection. Using short codes in our naming convention also ensures we have consistency in naming between OS Select+Build and the OS NGD APIs.

An example of how these short codes are used is below, with the example showing a file name which would be created for an order of the Built Address Feature Type within the OS NGD GB Address Collection of the OS NGD Address Theme:

add_gb_builtaddress

A full list of the short codes we use in OS Select+Build and the OS NGD APIs is detailed in the following table:

Through the OS NGD, Ordnance Survey aims to iterate and release data enhancements quicker than ever before. We want to be able to do this without disrupting customers who have adopted data schemas and are heavily reliant on a specification remaining the same for a longer period of time. With this in mind, the OS NGD is able to run multiple data schema versions for a single feature type at any given time.

When we release a new data schema version in the OS NGD, the changes will be visible on the feature type pages of this documentation platform. As you can see from the image below, each attribute on a feature type page states which data schema version it is present within, with the Version Date attribute in the example below being present in both data schema versions 1.0 and 2.0:

How has data schema versioning been implemented?

As new enhancements are made to a given feature type in the OS NGD which require the schema to be uplifted (for example, new attributes being added, resulting in a major schema version increment from 1.0 to 2.0), the new data schema version will become available via the OS NGD access services (i.e. OS Select+Build and the OS NGD APIs).

There are two types of version increments that can be applied:

• Minor: A non-breaking change that does not usually impact a customer’s implementation of the data, for example, the addition of an attribute value to a code list.

• Major: A significant breaking change that usually impacts a customer’s implementation of the data, for example, the addition or removal of an attribute.

When a data schema undergoes a minor version increment, the previous version will no longer be available. This is because the change is deemed to be so small that there is little to no work involved in customers migrating to the latest version of the data.

When a data schema undergoes a major version increment, the previous version will become known as being in 'maintenance' and the new data schema version will be known as the ‘latest’. This reflects an understanding of the work required for customers to move to a new version and allows time for this to happen.

When using the OS NGD access services, you will be able to choose which data schema version you want to use for feature types when ordering or interacting with the data where more than one major version exists. You can choose from data schema versions which are in the 'latest' or 'maintenance' states.

Older data schema versions (i.e. those in a maintenance state) will remain in the OS NGD for a period of time; it's important to note that these maintenance versions will continue to receive updates. Before any data schema version is retired for a given feature type (i.e. when it no longer receives updates and will be removed from the ordering and selection process), customer communications will be distributed, and a notice period will be issued to allow sufficient time for customers to upgrade to a newer version of a data schema.

Code list versioning

Code lists within the OS NGD have only one type of version increment applied: major.

A code list will undergo a major version change when a new code list value is added to it. Values will never be removed from a code list because this would impact temporal filtering within the OS NGD.

When a code list undergoes a major version increment, all feature types that implement the code list will undergo a minor version increment, reflecting the data change that will occur.

Worked example

In the worked example below, we demonstrate how a feature type has new major data schema versions released (v2.0 and then v3.0), while maintaining older data schema versions (v1.0 and then v2.0), before the original data schema version (v1.0) moves into end of life and is retired.

• In this example, the feature type starts with a single data schema version (v1.0), known as the latest data schema version.

• At a point in the future, data enhancements are made which require the data schema version to be uplifted, so a second major data schema version (v2.0) is released. As there can only be one latest data schema version (v2.0), the original data schema version (v1.0) drops down into maintenance – but it still receives updates and is still accessible to customers via the OS NGD access services.

• Further again into the future, additional new enhancements are made to the feature type, requiring a third major data schema version (v3.0) to be released. Again, as before, there can only be one latest data schema version for a feature type (v3.0), so the second data schema version (v2.0) drops down into maintenance. Two major data schema versions (v1.0 and v2.0) are now in maintenance, but again, both are still receiving updates and are accessible to customers via the OS NGD access services.

• At a future point, and after customer communications have been distributed and a formal notification period has elapsed, it is decided to retire the original data schema version (v1.0). V1.0 moves into the end of life state, where it stops receiving updates and can no longer be accessed by customers via the OS NGD access services. V3.0 remains the latest data schema version and v2.0 remains in maintenance, with both data schema versions receiving updates and being accessible to customers via the OS NGD access services.

Annual Full Supply orders and data schema versioning

If you select an Annual Full Supply frequency for your OS NGD data order in OS Select+Build, we will provide you with the data as it was on 01 January of the current year. This means if a new feature type or a new data schema version of an existing feature type was released after 01 January and you order either of these as part of your Annual Full Supply, you will receive an empty data package for the newly released feature type / new data schema version of an existing feature type. The data for the new feature type / new data schema version of an existing feature type will then be included in your supply on the next 01 January after the release.

For example, the March 2025 OS NGD data enhancements release contained 3 new feature types (Building Access Location, Crowd Sourced Name Point, and Street Light), and 11 new data schema versions (Building v4.0, Building Part v2.1, Land v3.1, Path Link v2.0, Rail v3.1, Road Link v4.0, Road Track Or Path v3.1, Site v2.2, Site Access Location v2.0, Structure v3.1, and Water v3.1). The data for the new feature types and the new data schema versions will not be part of Annual Full Supply orders until 01 January 2026.

For example, the September 2025 OS NGD data enhancements release contained 6 new feature types (Royal Mail Address, Royal Mail Address, Bus Lane, Cycle Lane, Tidal Boundary Continuous High and Tidal Boundary Continuous Low), and 13 new data schema versions for existing feature types (Built Address v3.0, Built Address v3.0, Historic Address v3.0, Historic Address v3.0, Land v3.2, Non-Addressable Object v3.0, Non-Addressable Object v3.0, Path Link v3.0, Pre-Build Address v3.0, Pre-Build Address v3.0, Road Link v5.0, and Site v1.3 and 2.4) and 3 new data schema versions for existing addressing related components (Alternate Address v3.0, Other Classification v3.0 and Related Entity v3.0). The data for the new feature types and the new data schema versions will not be part of Annual Full Supply orders until 01 January 2026.

To get access to the OS NGD you must first log into the OS Data Hub. The OS NGD is accessible via both the Premium Plan and Public Sector Plan on the OS Data Hub.

Geographic filtering

There are three options within OS Select+Build (the OS NGD download service) in relation to the geographic extent of your order. These are:

• Great Britain: Receive all data for the whole of Great Britain.

• Customer Specified Area: Draw an area of interest (AOI) and only receive the data which intersects this area.

• Pre-defined Area: Select a pre-defined area, and only receive the data which intersects this area.

Order update options

When accessing the OS NGD, the following order update options will be available:

• One Off Full Supply

• Regular Full Supply

• Change-Only Update (COU; after an initial Full Supply)

• No Update

The following frequencies will be available dependent on the type of order you place:

• Daily Supply: This will provide you with the latest updates OS have loaded and verified for publication since the previous day as a COU file.

• Monthly Supply: Either a Full Supply or COU Supply of all the changes which have occurred in the previous month.

• Annual Supply: A Full Supply of the data to show how the data looked at the end of each year.

Further details about the options available to you can be found further down on this page.

Update files

If you choose to receive a COU supply for your CSV data, this can be provided on either a daily or monthly frequency. In both cases, your COU file will contain any changes which have been made to the underlying data within the selected time frequency. If no changes have been made to a selected feature type of your choice, then you will receive a blank COU file.

File supply

If you use OS Select+Build to access the OS NGD, then a separate download file will be provided for each feature type you order. For example, if your selected theme has two feature types you will be supplied with two separate files (CSV or GeoPackage) as part of your order.

Ordering combinations

The following tables summarise the different options available to you dependent on what you specify when ordering your data through OS Select+Build.

For the purposes of the tables below, the following definitions are being used:

• Unfiltered means a Great Britain supply with no further attribute filters applied.

• Filtered means an order for data which either has a geographic filter applied or an attribute filter applied.

GPKG files

CSV files

Currency of OS NGD data

OS Select+Build and OS NGD API – Features

Whether accessing OS NGD data through OS Select+Build or OS NGD API – Features, the following currency of the data will apply:

For collections that are not updated daily, the table below provides the date of the last update; it also shows the version of the OS MasterMap product to which the OS NGD data corresponds, if applicable:

OS NGD API – Tiles

When accessing OS NGD data through OS NGD API – Tiles, the data currency is weekly for the basemap and variable for the four data overlays – please see the 'What data is available' (for OS NGD API – Tiles) page for more information on update frequency, available feature types and available attribution for this API.

Feature counts for the OS NGD Transport Theme

Feature counts are detailed below for the Routing and Asset Management (RAMI) and Transport Network Collections of the OS NGD Transport Theme. These feature counts will be updated monthly to reflect data currency for these collections.