#print
Even more powerful is to use two context
searches for the pair of addresses
in front of a command.  For example
  /abc/,/def/p
will print all lines from the one that
contains "abc" to the one that contains
"def".  In this directory is a file
"phone".  On every line between
"Pinson" and "Johnson" change "tel" to "ext".
(Again, print the whole file first to see
what's going on here and why the file is bad.)
Then rewrite the corrected file and
type "ready".
#create Ref
 telephone numbers

McIlroy M D       ext 6050
Aho A V           ext 4862
Baker B S         ext 6503
Cherry L L        ext 6067
Knowlton K        ext 2328
Morris R          ext 3878
Ossanna J F       ext 3520
Thompson K        ext 2394

Pinson E N        ext 2582
Bourne S R        ext 7419
Elliot R J        ext 2879
Fraser A G        ext 3685
Johnson S C       ext 3968
Kernighan B W     ext 6021
Ritchie D M       ext 3770
Vollaro J R       ext 6321
#create phone
 telephone numbers

McIlroy M D       ext 6050
Aho A V           ext 4862
Baker B S         ext 6503
Cherry L L        ext 6067
Knowlton K        ext 2328
Morris R          ext 3878
Ossanna J F       ext 3520
Thompson K        ext 2394

Pinson E N        tel 2582
Bourne S R        tel 7419
Elliot R J        tel 2879
Fraser A G        tel 3685
Johnson S C       tel 3968
Kernighan B W     ext 6021
Ritchie D M       ext 3770
Vollaro J R       ext 6321
#user
#cmp phone Ref
#log
#next
53.1a 10
52.2c 5