code: public void writeString(String value)
          throws IOException
      {
          if (value == null) {
              os.write('N');
          }
          else {
              int len = value.length();
  
              os.write('S');
              os.write(len >> 8);
              os.write(len);
  
              printString(value);
          }
      }
docs: Writes a string value to the stream using UTF-8 encoding.
  The string will be written with the following syntax:
  
  <code><pre>
  S b16 b8 string-value
  </pre></code>
  
  If the value is null, it will be written as
  
  <code><pre>
  N
  </pre></code>
  
  @param value the string value to write.