public override void WriteTo(XmlWriter w)
 {
     w.WriteDocType(Name, PublicId, SystemId, InternalSubset);
 }
 public override void WriteDocType(string name, string pubid, string sysid, string subset)
 {
     writer.WriteDocType(name, pubid, sysid, subset);
     state = WriteState.Prolog;
 }