# 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="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2Fbz2Cqhvt1rZWqOO9B2OG%2F2.png?alt=media" 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="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2FQVyCmk186UCaVLg2GVnF%2F3.png?alt=media" 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="https://1897589978-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FcNpJpLP8RROUaWVQo5ea%2Fuploads%2F5UAtawQBfx84a9cAgN6H%2F4.png?alt=media" 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 %}