Many of the obtions listed above are self-evident, but some call for more comments.
Modern links normally allow bi-directional operation and the "suppress go ahead" option is enabled.
The echo option is enabled, usually by the server, to indicate that the server will echo every character it receives. A combination of "suppress go ahead" and "echo" is called character at a time mode meaning that each character is separately transmitted and echoed.
There is an understanding known as kludge line mode which means that if either "suppress go ahead" or "echo" is enabled but not both then telnet operates in line at a time mode meaning that complete lines are assembled at each end and transmitted in one "go". * linemode
This option replaces and supersedes the line mode kludge.
This option controls where the special flow control effects of Ctrl-S/Ctrl-Q are implemented.