code: public void mark(int readAheadLimit) throws IOException {
          String msg = JspCoreException.getMsg("jsp.error.xml.operationNotSupported", new Object[] {"mark()","UTF-8"});
          throw new IOException(msg);
      }
docs: Mark the present position in the stream.  Subsequent calls to reset()
  will attempt to reposition the stream to this point.  Not all
  character-input streams support the mark() operation.
  
  @param  readAheadLimit  Limit on the number of characters that may be
  read while still preserving the mark.  After
  reading this many characters, attempting to
  reset the stream may fail.
  
  @exception  IOException  If the stream does not support mark(),
  or if some other I/O error occurs