> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-apis/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-apis/accessing-os-apis/os-linked-identifiers-api/what-data-is-available.md).

# What data is available?

Numerous OS data products are available through the OS Linked Identifiers API.

The lists in the following sub-sections include a link to more information about the underlying OS product, the product category (Premium vs. Open), the feature type name, and the identifier used in the dataset.

Click the product name links to find more information about each dataset.

## Topographic area

* **OS product**: [OS MasterMap Topographic Layer](https://docs.os.uk/os-downloads/topography/os-mastermap-topography-layer/os-mastermap-topography-layer-technical-specification)
* **Description**: Polygon limited to building outline or road surface area.
* **Data category**: Premium
* **Feature type name**: `TopographicArea`
* **Identifier:** TOID

## Road link

* **OS product**: [OS MasterMap Highways](https://docs.os.uk/os-downloads/networks/os-mastermap-highways-network-routing-and-asset-management-information/os-mastermap-highways-network-routing-and-asset-management-information-technical-specification)
* **Description**: Section of road from junction to junction.
* **Data category**: Premium
* **Feature type name**: `RoadLink`
* **Identifier**: TOID

## Road

* **OS product**: [OS MasterMap Highways](https://docs.os.uk/os-downloads/networks/os-mastermap-highways-network-routing-and-asset-management-information/os-mastermap-highways-network-routing-and-asset-management-information-technical-specification)
* **Description**: Collection of `RoadLinks` with a given name.
* **Data category**: Premium
* **Feature type name**: `Road`
* **Identifier:** TOID

## BLPU

* **OS product**: [AddressBase Premium](https://docs.os.uk/os-downloads/addressing-and-location/addressbase-premium/addressbase-premium-technical-specification)
* **Description**: An address location with postal address. BLPU = Basic Land and Property Unit. UPRN = Unique Property Reference Number.
* **Data category**: Premium
* **Feature type name**: `BLPU`
* **Identifier**: UPRN

## Street

* **OS product**: [OS MasterMap Highways](https://docs.os.uk/os-downloads/networks/os-mastermap-highways-network-routing-and-asset-management-information/os-mastermap-highways-network-routing-and-asset-management-information-technical-specification)
* **Description**: An identifier allocated to a street by a local authority. USRN = Unique Street Reference Number.
* **Data category**: Premium
* **Feature type name**: `Street`
* **Identifier:** USRN

## Open road junctions

* **OS product**: [Open Roads](https://docs.os.uk/os-downloads/networks/os-open-roads/os-open-roads-technical-specification)
* **Description**: Road junctions from our OpenData product.
* **Data category**: Open
* **Feature type name**: `ORRoadNode`
* **Identifier:** GUID

## Open road links

* **OS product**: [Open Roads](https://docs.os.uk/os-downloads/networks/os-open-roads/os-open-roads-technical-specification)
* **Description**: Road sections from our OpenData product
* **Data category**: Open
* **Feature type name**: `ORRoadLink`
* **Identifier:** GUID


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