2.11BSD/src/share/learn/editor/L20.2a

#print
You can now change a line of a file by a slow procedure: delete the
old version and insert the new one.  For example, you could replace
line 4 of a file with
   4d
   3a
   new version of line 4
   .
right?  OK, try that.  There is a file named "words" in this
directory and line 4 contains a mistyped word.  Correct it and
rewrite the file; then type "ready".
#create Ref
bear
begin
belief
believe
belt
bend
#create words
bear
begin
belief
beleive
belt
bend
#user
#cmp words Ref
#log
#next
20.2b 5