# EPUB container.xml

Source: https://xmlvalid.com/schemas/epub-ocf-container

> The META-INF/container.xml of an EPUB, which tells reading systems where the package document is.

A reading system opens META-INF/container.xml first and follows its rootfile to the package document. EPUB 2 and EPUB 3 use the same container format.

- Type: RelaxNG Compact
- Version: 3.0 to 3.3
- Namespace: `urn:oasis:names:tc:opendocument:xmlns:container`
- Root element: `container`
- Publisher: W3C EPUB 3 Community Group (epubcheck) (MIT (IDPF)), source: https://github.com/w3c/epubcheck/tree/main/src/main/resources/com/adobe/epubcheck/schema/30
- Validate against it: https://xmlvalid.com/validate?schema=epub-ocf-container

## Notes

- On its own, whether the rootfile path exists inside the .epub is not checked; drop the whole .epub on the validator's Upload tab and it is.
- The example is by xmlvalid.com.