anchor.diff:  enc_opt(exit_on_close)   -> ?INET_LOPT_EXITONCLOSE;
   enc_opt(high_watermark)  -> ?INET_LOPT_TCP_HIWTRMRK;
   enc_opt(low_watermark)   -> ?INET_LOPT_TCP_LOWTRMRK;
  -enc_opt(bit8)            -> ?INET_LOPT_BIT8;
   enc_opt(send_timeout)    -> ?INET_LOPT_TCP_SEND_TIMEOUT;
   enc_opt(send_timeout_close) -> ?INET_LOPT_TCP_SEND_TIMEOUT_CLOSE;
   enc_opt(delay_send)      -> ?INET_LOPT_TCP_DELAY_SEND;
  
positive.code: type_opt_1(exit_on_close)   -> bool;
  type_opt_1(low_watermark)   -> int;
  type_opt_1(high_watermark)  -> int;
  type_opt_1(bit8) ->
      {enum,[{clear, ?INET_BIT8_CLEAR},
  	   {set,   ?INET_BIT8_SET},
  	   {on,    ?INET_BIT8_ON},
  	   {off,   ?INET_BIT8_OFF}]};
  type_opt_1(send_timeout)    -> time;
  type_opt_1(send_timeout_close) -> bool;
  type_opt_1(delay_send)      -> bool;
  
negative.code: dec_opt(?INET_LOPT_EXITONCLOSE)   -> exit_on_close;
  dec_opt(?INET_LOPT_TCP_HIWTRMRK)  -> high_watermark;
  dec_opt(?INET_LOPT_TCP_LOWTRMRK)  -> low_watermark;
  dec_opt(?INET_LOPT_TCP_SEND_TIMEOUT) -> send_timeout;
  dec_opt(?INET_LOPT_TCP_SEND_TIMEOUT_CLOSE) -> send_timeout_close;
  dec_opt(?INET_LOPT_TCP_DELAY_SEND)   -> delay_send;
  