# Product supply

## Available formats

OS OML is available in the following formats:

* Vector: GML (Geography Markup Language) v.3.2.1 Simple Features and schema, which is zipped as a single file using gzip.
* Vector: ESRI shapefile, with each tile dataset zipped using gzip.
* Vector: GeoPackage, with a single zipped file for a national set (Great Britain).
* Raster: GeoTIFF, compressed using 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.

## Supply mechanism

OS OML is supplied as an online download, which is available with no registration required. Data can be downloaded in various formats from the [OS Data Hub](https://osdatahub.os.uk/data/downloads/open/OpenMapLocal).

## Coverage and file sizes

* Coverage is Great Britain (i.e. England, Wales and Scotland).

### GML

* 55 tiles, each covering 100km x 100km, comprise the national set (Great Britain)
* Each tile comprises up to 71 feature codes
* Features that cross the tile edge are not split and are therefore duplicated within adjacent tiles (as explained in the edgematching section)
* Tile sizes range from 10KB to approximately 200MB zipped
* The file size of the national set (Great Britain) is 2.4GB zipped

### ESRI shapefile

* 55 tiles, each covering 100km x 100km, comprise the national set (Great Britain)
* Each tile comprises a set of up to 20 shapefiles
* Each shapefile holds a single feature type
* Features that cross the tile edge are not split and are therefore duplicated within adjacent tiles (as explained in the edgematching section)
* Tile sizes range from <17KB to approximately 181MB zipped
* The data is not encrypted
* The file size of the national set (Great Britain) is 2.4GB zipped

### GeoPackage

* Only available as a national set (Great Britain)
* Single file contains all the feature types
* The data is not encrypted
* The file size of the national set (Great Britain) is 3.8GB zipped

### Colour raster GeoTIFF

* 10 588 tiles, each covering 5km x 5km, comprise the national set (Great Britain)
* GeoTIFF and compressed using LZW compression
* Tile sizes range from 6KB to approximately 921MB zipped
* The data is not encrypted
* The file size of the national set (Great Britain) is 15GB zipped

## Currency

OS OML is supplied to customers bi-annually in April and October, incorporating any updates made by the revision programme. More information about the [OS MasterMap revision policy](https://www.ordnancesurvey.co.uk/business-government/tools-support/mastermap-topography-support/revision-policy) is available on the OS website.


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