<dtd systemId = anyURI publicId = non empty token />
Use the DTD specified by this element to constrain the document.
Note that
if a document contains a document type declaration (<!DOCTYPE>) which defines elements,
or if the root element of a document has xsi:schemaLocation
/xsi:noNamespaceSchemaLocation
attributes,
of if a document contains a <?xxe-relaxng-schema location="..."?> processing instruction,
the grammar specified this way is used and the DTD specified in the configuration file is ignored.
Example:
<dtd publicId="-//W3C//DTD XHTML 1.0 Strict//EN" systemId="dtd/xhtml1-strict.dtd" />
It possible to use both a schema or relaxng configuration element and a dtd
configuration element but in this case, the dtd
configuration element cannot be used to specify a content model. It may be used to specify a set of character entities.