Convert XML data into a predefined Perl data structure and back

 The XML::Structured module provides a way to convert XML data into a
 predefined Perl data structure and back to XML. Unlike with modules like
 XML::Simple it is an error if the XML data does not match the provided
 skeleton (the "dtd"). Another advantage is that the order of the attributes
 and elements is taken from the dtd when converting back to XML.