> For the complete documentation index, see [llms.txt](https://docs.devland.is/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.devland.is/reference.md).

# REFERENCE

- [Problems](https://docs.devland.is/reference/problems.md)
- [400 Validation Failed](https://docs.devland.is/reference/problems/validation-failed.md)
- [400 Attempt Failed](https://docs.devland.is/reference/problems/attempt-failed.md)
- [403 Bad Subject](https://docs.devland.is/reference/problems/bad-subject.md)
- [400 500 Template API Error](https://docs.devland.is/reference/problems/template-api-error.md)
- [Glossary](https://docs.devland.is/reference/glossary.md)