When no command is specified, xon runs 'xterm -ls'. It additionally specifies the application name to be 'xterm-remote-host' and the window title to be '-fIremote-host'.
Xon can only work when the remote host will allow you to log in without a password, by having an entry in the .rhosts file permitting access.
Note that the options follow the remote host name (as they do with rlogin).
Runs xhost locally to add the remote host to the host access list in the X server. This won't work unless xhost is given permission to modify the access list.
Normally, xon disconnects the remote process from stdin, stdout and stderr to eliminate the daemon processes which usually connect them across the network. Specifying the -debug option leaves them connected so that error messages from the remote execution are sent back to the originating host.
This specifies a different application name and window title for the default command (xterm).
Normally xon passes the -ls option to the remote xterm; this option suspends that behaviour.
This changes the screen number of the DISPLAY variable passed to the remote command.
By default, xon simply uses rsh/remsh/rcmd to connect to the remote machine using the same user name as on the local machine. This option cause xon to specify an alternative user name. This will not work unless you have authorization to access the remote account, by placing an appropriate entry in the remote users .rhosts file.
Xon has no way to send the appropriate X authorization information to the remote host.