code: public static String decode(byte[] tpdu, KNXAddress dst)
  	{
  		if (tpdu.length < 1)
  			throw new KNXIllegalArgumentException("TPDU length too short");
  		final String s = decodeTPCI(tpdu[0] & 0xff, dst);
  		if (tpdu.length > 1)
  			return s + ", " + decodeAPCI(getAPDUService(tpdu));
  		return s;
  	}
docs: Decodes a protocol data unit into a textual representation.
  <p>
  Currently, the transport layer protocol control information (TPCI) and the
  application layer protocol control information (APCI) is decoded. Decoding might be
  extended in the future.<br>
  The optional KNX destination address helps to determine the exact transport layer
  service.
  
  @param tpdu transport layer protocol data unit to decode
  @param dst KNX destination address belonging to the TPDU, might be
  <code>null</code>
  @return textual representation of control information in the TPDU