DTD in Xerces

[Alexey Kuleshov]

Hi! I have the following task: I parse (with the help of xerces-j) the xml-file, to which corresponds certain DTD. After that my program builds a representation of the xml-document as JTree which the user can change at the desire (add/move nodes of a tree - elements from the xml-document, change attribute values). The question is: How to check, that changes made by an user in a tree (i.e. in the xml-document) are done according to DTD (i.e. rules of correct enclosure of elements are observed, correspondence of values to types of attributes etc.)? Maybe somebody already solved the similar task or knows an appropriate URL.