The switch hook (%) character is used to signal that you are
    about to enter a command. Normally, all text typed is considered
    part of the conversation. However, when you type a switch hook,
    all characters up to the next carriage return (or switch hook)
    are treated as a command.

    The switch hook is optional if you are not carrying on a
    conversation when you enter the command.

    The switch hook character is always displayed in column 1 of line
    2. The default character is the percent sign (%).