Object oriented style:
class XMLWriter {Procedural style:
bool xmlwriter_start_dtd ( resource xmlwriter, string qualifiedName [, string publicId [, string systemId]] )Starts a DTD.
xmlwriterOnly for procedural calls. The XMLWriter resource that is being modified. This resource comes from a call to xmlwriter_open_uri() or xmlwriter_open_memory().
qualifiedNameThe qualified name of the document type to create.
publicIdThe external subset public identifier.
systemIdThe external subset system identifier.