     When you want to change or erase something you've typed on a "command
line," you can use many of the keystrokes that are used in the Emacs text
editor.  For instance, to erase one character to the left of the "cursor," you
use the DEL key.  To erase the entire line to the left of the cursor, use the
commercial-at sign (@).

     Inserting and erasing characters in the middle of the line requires that
you move the cursor with keystrokes that involve either the CONTROL key or the
ESCAPE key.  To move the cursor back one letter at a time, you press the
CONTROL key and hold it down while typing the letter b.  To go back one word
at a time, you press the ESCAPE key, then release it and type the letter b.
To move forward, you use the CONTROL and ESCAPE keys with the letter f.  If
you want to go to the beginning of the line, use the CONTROL key with the
letter a, and to go to the end of the line, use the CONTROL key with the
letter e.

     Those are the most useful keystrokes, though there are others you might
find handy.  Check the Emacs Text Editor Users' Guide (Order No. CH27).

     There is one other keystroke that comes in handy for big mistakes, such
as when you type a carriage return to conclude a command line and then
discover that you made a mistake.  You can get the mistakenly typed line back
by typing the CONTROL key with the letter y.  That will redisplay the line,
and you can then correct it, rather than type the whole line again.

     When you are not using the Multics video system, you can erase only one
character at a time or the entire line.

     To erase one character at a time, type the number sign (#).  That will
erase the character to its left or, if there is blank space immediately to its
left, it will erase all that space back to the next character.  To erase the
entire line to the left, type the commercial-at sign (@).  Notice whether the
symbols appear on your screen or actually erase what's there.  If the former,
that means the video system is not on, and thus you can only erase characters
with the number sign and commercial-at sign.  If the latter, then the video
system is on, so you can use all of the keystrokes discussed above.
     
     You can experiment with this now if you want to by pressing function key
F2.  That will put you at "command level" where you can type command lines
and erase them.
