readElements(acc);
cp.content = readElements(acc);
  private void readContentParticle(StringBuffer acc)    throws IOException, XMLStreamException  {    if (tryRead('('))      {        acc.append('(');        readElements(acc);      }    else      {        acc.append(readNmtoken(true));        mark(1);        char c = readCh();        switch (c)          {          case '?':          case '*':          case '+':            acc.append(c);            break;          default:            reset();          }      }  }