In the xmldata attribute of DAL objects, an xsd file is referenced.

DirectoryModelXmlData3_5_0.xsd

More specifically:
<entity-definition xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="../../../../../../../xml-validation/
conf/schema/DirectoryModelXmlData3_5_0.xsd">

Does anyone know where to find this file?
We are manipulating the attribute, and I think we could perhaps validate
it against the schema