> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-downloads/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/os-downloads/products/buildings-and-infrastructure-portfolio/os-mastermap-topography-layer-building-height-attribute/os-mastermap-topography-layer-building-height-attribute-technical-specification/product-supply.md).

# Product supply

## Product supply format <a href="#bookmark1" id="bookmark1"></a>

Building Height Attribute data is supplied in comma-separated values (CSV) file format. Files will not be compressed.

## Product supply mechanism <a href="#bookmark2" id="bookmark2"></a>

OS MasterMap Topography Layer – Building Height Attribute is supplied as an online download. You can download data in CSV format from the [OS Data Hub](https://osdatahub.os.uk/).

The product is currently still available for customers to request through [OS Orders](https://orders.ordnancesurvey.co.uk/sso/login.shtml).

Building Height Attribute is supplied in 5 km² geographic chunks. Each 5 km² chunk will contain Building Height Attribute values for any building polygon that intersects that area. As such, any Building Height Attribute values that fall across tile boundaries in contiguous tiles will be duplicated.

Tiles are supplied with all available data contained within them. Not all 5 km² tiles will have complete coverage.

## File naming in the product <a href="#bookmark3" id="bookmark3"></a>

The CSV files are named as the 5km2 chunks they correspond to, for example:

* **TQ2060** for TQ26SW
* **TQ2065** for TQ26NW
* **TQ2560** for TQ26SE
* **TQ2565** for TQ26NE


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