Telnet option code

I asked some question that how can I communicate with telnet server previously.
Now I can understand Telnet command specification that is consist of three bytes like that 255 253 24.
When my telnet connect to telnet server, telnet server send 15bytes below
255 253 24 => IAC DO TERMINAL-TYPE (I can undrestand this command option byte)
255 253 31 => IAC DO ? (I can't undrestand this command option byte)
255 253 35 => IAC DO X-DISPLAY-LOCATION (I can undrestand this command option byte)
255 253 39 => IAC DO ? (I can't undrestand this command option byte)
255 253 36 => IAC DO ? (I can't undrestand this command option byte)

I tried to find  third option codes. I failed to find them expt 24,35.
So somebody help me where can I found that kind of option byte explanation
and how my client have to answer.
I got another question about some telnet server
one of telnet server send those byte above, but one of telnet server send different code that is simple
255 253 36
Could tell me that reason....
thanks.