These constants are used when requesting a pseudo-terminal (via Net::SSH::Connection::Channel#request_pty). The descriptions for each are taken directly from RFC 4254 ("The Secure Shell (SSH) Connection Protocol"), tools.ietf.org/html/rfc4254.
7 bit mode.
8 bit mode.
Enable echoing.
Echo control characters as ^(Char).
Visually erase chars.
Kill character discards current line.
Visual erase for line kill.
Echo NL even if ECHO is off.
Canonicalize input lines.
Map CR to NL on input.
Enable extensions.
Ignore CR on input.
The ignore parity flag. The parameter SHOULD be 0 if this flag is FALSE, and 1 if it is TRUE.
Ring bell on input queue full.
Map NL into CR on input.
Enable checking of parity errors.
Enable signals INTR, QUIT, [D]SUSP.
Strip 8th bit off characters.
Translate uppercase characters to lowercase.
Any char will restart after stop.
Enable input flow control.
Enable output flow control.
Don't flush after interrupt.
Translate carriage return to newline (output).
Convert lowercase to uppercase.
Map NL to CR-NL.
Newline performs a carriage return (output).
Translate newline to carriage return-newline (output).
Enable output processing.
Parity enable.
Mark parity and framing errors.
Odd parity, else even.
Retype pending input.
Stop background jobs from output.
Specifies the input baud rate in bits per second.
Specifies the output baud rate in bits per second.
Toggles the flushing of terminal output.
Another suspend character.
End-of-file character (sends EOF from the terminal).
End-of-line character in addition to carriage return and/or linefeed.
Additional end-of-line character.
Erase the character to left of the cursor.
Character to flush output.
Interrupt character; 255 if none. Similarly for the other characters. Not all of these characters are supported on all systems.
Kill the current input line.
Enter the next character typed literally, even if it is a special character.
The quit character (sends SIGQUIT signal on POSIX systems).
Reprints the current input line.
Continues paused output (normally control-Q).
Prints system status line (load, command, pid, etc).
Pauses output (normally control-S).
Suspends the current program.
Switch to a different shell layer.
Erases a word left of cursor.
Enable input and output of uppercase characters by preceding their lowercase equivalents with "".