Object oriented style:
class XMLWriter {Procedural style:
bool xmlwriter_write_dtd ( resource xmlwriter, string name [, string publicId [, string systemId [, string subset]]] )Writes a full DTD.
xmlwriter仅用于过程调用。resource 是被修改的 XMLWriter 资源。此资源来自对 xmlwriter_open_uri() 或 xmlwriter_open_memory() 的调用
nameThe DTD name.
publicIdThe external subset public identifier.
systemIdThe external subset system identifier.
subsetThe content of the DTD.