This is primarily used to generate XHTML from HTML input.
Used to exercise the pattern recognition engine, which can be used with the reader interface to the parser.
e Xist come with default setting that may prevent files from being added that are associated with a namespace once a schema is saved in the registry.
It allows to select some nodes in the document based on an XPath (subset) expression.
Apart from the built-in DTD support in parsers, lxml currently supports three schema languages: DTD, Relax NG and XML Schema.
I got no message about needing at target space as you did.
To bad that it doesn't work at all at my work installation though.
For example, in my xsd, some attributes are required but the session inserts lines into the target although the atribute is null.