2.11BSD/src/share/learn/editor/L65.1a

#print
A strange, and not often important command, is the 'l' (list) command.
When it is needed, though, it is vital.  It is almost identical to 'p'
(print) except that control characters (like tab or backspace) are
printed in a way that lets you see what they are no matter what the
terminal does.  From time to time strange characters will sneak into
your files; they won't show when you print them, and yet they will
confuse you.  For example, you might be unable to find a line by
searching for it with
   /abc/
and yet it would print as "abc" if there were
a funny character in the line between 'a' and 'b'.
Funny characters are generated by hitting the control
keys on the terminal; they print as '^' followed
by a character.
There is a file "weird" in this directory.  Print
it both with "1,$p" and "1,$l" and observe the difference.
Then leave the editor.  Which word on the last line has a funny
character before it? Type "answer WORD" where WORD is that word.
#create weird
This line	has	tabs	in	it.
So		does		this	one.
Here is a line ____with backspaces of a useful sort,
which show how underlining on printed output is done.
These backspacesonlyconfuse matters.

there is a strange character in	this line even though it prints ok.
#copyin
#user
#uncopyin
#match this
#log
#next
66.1a 10