code: public void setFlattenWriter(Writer w, boolean inclComments,
                                   boolean inclConditionals, boolean inclPEs)
      {
          mFlattenWriter = new DTDWriter(w, inclComments, inclConditionals,
                                         inclPEs);
      }
docs: Method that will set specified Writer as the 'flattening writer';
  writer used to output flattened version of DTD read in. This is
  similar to running a C-preprocessor on C-sources, except that
  defining writer will not prevent normal parsing of DTD itself.