> 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/maps-and-imagery-portfolio/os-openmap-local/os-openmap-local-technical-specification/code-lists/tidalboundaryclassification.md).

# TidalBoundaryClassification

## Code List: TidalBoundaryClassification

| Value           | Description                                                                                                                                                                                                                                            |
| --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| High Water Mark | In England and Wales, this is the mean level of all the high tides; in Scotland this is the mean level of the spring high tides. In places where there is no Foreshore (e.g. vertical cliffs), the TidalBoundary is classified as the High Water Mark. |
| Low Water Mark  | In England and Wales, this is the mean level of all the low tides; in Scotland, this is the mean level of the spring low tides. When there is Foreshore, this defines the lower limit of the Foreshore.                                                |


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