code: public void mapRole(PdfName used, PdfName standard) {
          PdfDictionary rm = (PdfDictionary)get(PdfName.ROLEMAP);
          if (rm == null) {
              rm = new PdfDictionary();
              put(PdfName.ROLEMAP, rm);
          }
          rm.put(used, standard);
      }
docs: Maps the user tags to the standard tags. The mapping will allow a standard application to make some sense of the tagged
  document whatever the user tags may be.
  @param used the user tag
  @param standard the standard tag