4.3BSD-UWisc/lib/learn/editor/L30.2d

#print
In this directory is a file named "airport"
whose second line says "xx" where it should say
"ne".  Edit the file, change those letters, and
rewrite the file.  Then type "ready".
#create Ref
idlewild
newark
laguardia
#create airport
idlewild
xxwark
laguardia
#user
#cmp airport Ref
#log
#next
30.2e 5