> 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/land-and-terrain-portfolio/os-mastermap-sites-layer/os-mastermap-sites-layer-technical-specification/theme-definitions/utility-or-industrial.md).
# Utility or industrial
This theme includes sites where the following activities take place:
* The principles of chemistry are applied to materials to create different materials on a large scale.
* Energy (that is, electricity, gas or oil) is produced, refined, distributed or stored.
OS MasterMap Sites Layer (orange polygon) Utility or industrial theme – electricity production
| Functional site | Description |
| --------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Chemical works | A site where the principles of chemistry are applied to materials to create different materials. |
| Electricity distribution | A site used to handle electricity as part of the process of distributing electricity nationally. If the site is for domestic electricity supply then it is considered to be an electricity sub-station site and not captured as part of the initial release. |
| Electricity production | A site where electricity is generated on a large scale. |
| Gas distribution or storage | A site associated with the storing or supply of gas to users. |
| Oil distribution or storage | A depot where oil is stored. |
| Oil refining | A site where crude oil is refined. |
| Oil terminal | A storage point and distribution centre at the head of an oil pipeline |
The following features are included in the captured extent:
* Internal site access roads and paths.
* Buildings and structures associated with the operation of the site.
* Areas of man-made and natural surface totally surrounded by included areas.
* Areas of man-made and natural surface abutting included areas along a non-obstructing edge.
For marine oil terminals, include related berthing structures physically connected to the site The following features are **not** included in the captured extent:
* Site-related areas outside of perimeter fence (for example, car parking).
* Isolated mooring structures.
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