> 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/areas-and-zones-portfolio/boundary-line/boundary-line-product-information/structure-of-boundary-line.md).

# Structure of Boundary-Line

Boundary-Line data is output in a layered structure. This is a simplified file structure whereby the boundaries are supplied as individual files; for example, the county file contains only counties.

<figure><img src="/files/NtiDRgyu9Fe6bgRmE6fH" alt="An example of the GB directory and layered files." width="394"><figcaption><p><em>An example of the GB directory and layered files.</em></p></figcaption></figure>

<figure><img src="/files/2ZwvUHUsBhn0wRVwFC0b" alt="An example of the Polling Districts England directory and layered files."><figcaption><p><em>An example of the Polling Districts England directory and layered files.</em></p></figcaption></figure>

<figure><img src="/files/P8RnZsXfPoG8W8oVSTb8" alt="An example of the Wales directory and layered files."><figcaption><p><em>An example of the Wales directory and layered files.</em></p></figcaption></figure>

{% hint style="info" %}
Ceremonial and Historical counties are provided in separate directories called Supplementary\_Ceremonial and Supplementary\_Historical, respectively. Historic European Regions are provided in a separate Supplementary\_Historic\_European\_Region directory and Country outlines are provided in a separate Supplementary\_Country directory.
{% endhint %}


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