> 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.md).

# OS MasterMap Topography Layer – Building Height Attribute Technical Specification

OS MasterMap Topography Layer – Building Height Attribute is a dataset containing absolute and relative height values for buildings and selected structures contained within OS MasterMap Topography Layer. It is an enhancement to, and forms part of, OS MasterMap Topography Layer.

Building Height Attribute contains height values for buildings, tanks, chimneys (industrial) and glasshouses, specifically for Topographic Area features with the theme of ‘Buildings’ within OS MasterMap Topography Layer. It is necessary to join the Building Height Attribute data to the corresponding OS MasterMap Topography Layer feature to which it belongs, identified by the building topographic identifier (TOID). As such, an OS MasterMap Topography Layer licence is required to use the Building Height Attribute data.

The Building Height Attribute data provides full national coverage.

### Index

This technical specification includes the following sections:

* [Product supply](/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 structure](/os-downloads/products/buildings-and-infrastructure-portfolio/os-mastermap-topography-layer-building-height-attribute/os-mastermap-topography-layer-building-height-attribute-technical-specification/product-structure.md)
* [Feature type](/os-downloads/products/buildings-and-infrastructure-portfolio/os-mastermap-topography-layer-building-height-attribute/os-mastermap-topography-layer-building-height-attribute-technical-specification/feature-type.md)
* [Code list](/os-downloads/products/buildings-and-infrastructure-portfolio/os-mastermap-topography-layer-building-height-attribute/os-mastermap-topography-layer-building-height-attribute-technical-specification/code-list.md)
* [Example record](/os-downloads/products/buildings-and-infrastructure-portfolio/os-mastermap-topography-layer-building-height-attribute/os-mastermap-topography-layer-building-height-attribute-technical-specification/example-record.md)


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