
The modules in this directory are part of the schema that defines 
a vocabulary and grammar for EPUB 3 XHTML Content Documents, 
based on W3C HTML, with EPUB extensions. 

The modules are derived from the schemas used in the Nu Html Checker:
  https://validator.github.io/validator/ 

They are up-to-date with the commit indentified in the `LAST_UPDATE` file located
in this directory.

The file `epubcheck.patch` was created when first importing the HTML schemas,
to document how the type system was adapted. It is not intended to be applied
automatically as a patch file.

To update the schemas, run the helper script in `src/build/update-validator-schemas.sh`.
If anything goes wrong, try to follow the step of the scripts manually.