cified, then the xml
 output method should output PUBLIC followed by the public identifier
 and then the system identifier; otherwise, it should output SYSTEM
 followed by the system identifier. The internal subset should be empty.
 The value of the doctype-public property should be ignored unless the doctype-system
 property is specified.</p>
 <p>If the doctype-public or doctype-system properties are specified,
 then the html output method should output a document type declaration
 immediately before the f