Product supply mechanism and options

OS MasterMap Topography Layer incorporates a web-based ordering system that allows users to order their initial data supply and any updates, obtain price estimates and view details of their holdings on demand. The product is supplied as an online download. You can download data in its various formats from the OS Data Hub.

Please note that some formats are only available via OS Orders, Ordnance Survey's legacy ordering system; these formats are indicated in the following table:

Formats	AOI Supply	AOI Supply	GB Supply	GB Supply
	Geographic chunks	Non- geographic chunks	Geographic chunks	Non- geographic chunks
GeoPackage	Six files (one file per feature type)	Six files (one file per feature type)	N/A	N/A
Vector tiles	N/A	N/A	Six files (one file per feature type)	Six files (one file per feature type)
GML	2km² tiles*†	10MB files*†	5km² tiles	30MB files
GML	5km² tiles*	30MB files*	5km² tiles	30MB files
GML	10km² tiles*†	50MB files*†	5km² tiles	30MB files

* Feature Validation Dataset (FVDS) and Change-Only Update (COU) available.

† Only available via OS Orders.

Full GB coverage of OS MasterMap Topography Layer in GeoPackage format as a single AOI will be too large for the majority of GIS to handle.

There are two main supply options available for OS MasterMap Topography Layer: Full Supply or COU.

Initial Supply refers to the first order of OS MasterMap Topography Layer that a user makes, which will contain all features for all the layers selected for the area covered by the order. Upon Initial Supply, users can select whether they would like to receive future data updates as COU (user receives only the tiles/features that have changed since the last update) or a Full Supply (user receives all tiles/features regardless of whether they have changed since the last product update). COU data contains new and updated versions of features (known as Inserts and Updates, respectively), and information about departed features (known as Deletes); any feature within the area covered by the order that has not undergone any change will not be supplied.

The advantage of taking a COU Supply rather than a Full Supply is that, if applied regularly, the amount of data that must be processed and loaded is much smaller with a COU Supply. Users may request updates of the latest changes in their AOI, at any time, using the online service. Updates can either be for specified AOIs or GB wide.

It is advisable to apply COU updates for all the OS MasterMap layers to which you have subscribed at the same time to ensure cross-product synchronicity. OS MasterMap layers include the following products:

• OS MasterMap Topography Layer, OS MasterMap Sites Layer, OS MasterMap Building Height Attribute,

• OS MasterMap Greenspace Layer, OS MasterMap Highways Network – Roads, OS MasterMap Highways Network – Routing and Asset Management Information (RAMI), OS MasterMap Highways Network – Paths, and

• OS MasterMap Water Network Layer.