code: function encodeIREF( encoder, id ) {
  	var hi = (id & 0xF0000) >> 16,
  		lo = (id & 0xFFFF)
  
  	// Write opcode splitted inti 8-bit and 16-bit 
  	encoder.log(LOG.IREF, "iref="+id);
  	encoder.stream8.write( pack1b( PRIM_OP.REF | hi, false ) );
  	encoder.stream16.write( pack2b( lo, false ) );
  	encoder.counters.op_iref+=3;
  
  }
docs: Encode an 20-bit I-REF opcode