# XHTML 1.1

Source: https://xmlvalid.com/schemas/xhtml-1.1

> XHTML 1.1, the modular XHTML used by EPUB 2 books and some publishing pipelines.

XHTML 1.1 is XHTML 1.0 Strict assembled from modules, with Ruby annotations added. EPUB 2 content documents are XHTML 1.1.
This entry uses the flattened, single-file form of the DTD that W3C publishes.

- Type: DTD
- Version: 1.1 (second edition)
- Namespace: `http://www.w3.org/1999/xhtml`
- Root element: `html`
- Publisher: W3C (W3C Software and Document License), source: https://www.w3.org/TR/xhtml11/
- Validate against it: https://xmlvalid.com/validate?schema=xhtml-1.1

## Notes

- Named entities such as are only known when the DTD is read while parsing, which the browser cannot do for a DOCTYPE that points at w3.org. Use character references ( ) or the five XML entities.
- The example is by xmlvalid.com.