# Page Not Found

The URL `getting-started/os-ngd-core-principles/coordinate-reference-systems` does not exist.

You might be looking for one of these pages:
- [Coordinate reference systems](https://docs.os.uk/osngd/getting-started/os-ngd-fundamentals/coordinate-reference-systems.md)
- [Unique identifiers](https://docs.os.uk/osngd/getting-started/os-ngd-fundamentals/unique-identifiers.md)
- [Attribute information for feature types](https://docs.os.uk/osngd/getting-started/os-ngd-fundamentals/attribute-information-for-feature-types.md)
- [Terminology and access](https://docs.os.uk/osngd/getting-started/os-ngd-fundamentals/terminology-and-access.md)
- [Data schema versioning](https://docs.os.uk/osngd/getting-started/os-ngd-fundamentals/data-schema-versioning.md)

## How to find the correct page

1. **Browse the full index**: [/sitemap.md](https://docs.os.uk/osngd/sitemap.md) - Complete documentation index
2. **View the full content**: [/llms-full.txt](https://docs.os.uk/osngd/llms-full.txt) - Full content export

## Tips for requesting documentation

- For markdown responses, append `.md` to URLs (e.g., `/osngd/getting-started/os-ngd-fundamentals/coordinate-reference-systems.md`)
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