This module provides functions for validating XML Documents represented as XmlTree.

Unlike other popular XML validation tools the validation process returns a list of errors instead of aborting after the first error was found.

Before the document is validated, a lookup-table is build on the basis of the DTD which maps element names to their validation functions. After this initialization phase the whole document is traversed in preorder and every element is validated by the XmlFilter from the lookup-table.