code: public static DTDSubset readExternalSubset
          (WstxInputSource src, ReaderConfig cfg, DTDSubset intSubset, 
           boolean constructFully, int xmlVersion)
          throws XMLStreamException
      {
          FullDTDReader r = new FullDTDReader(src, cfg, intSubset, constructFully, xmlVersion);
          return r.parseDTD();
      }
docs: Method called to read in the external subset definition.