term% ls -F
term% cat index.txt
DIFF3(1)                    General Commands Manual                   DIFF3(1)

       diff3 - 3-way differential file comparison

       diff3 [ -ex3 ] file1 file2 file3

       Diff3  compares  three  versions  of  a file, and publishes disagreeing
       ranges of text flagged with these codes:

       ====            all three files differ

       ====1           file1 is different

       ====2           file2 is different

       ====3           file3 is different

       The type of change suffered in converting a given range of a given file
       to some other is indicated in one of these ways:

       f : n1 a        Text  is to be appended after line number n1 in file f,
                       where f = 1, 2, or 3.

       f : n1 , n2 c   Text is to be changed in the range line n1 to line  n2.
                       If n1 = n2, the range may be abbreviated to n1.

       The  original contents of the range follows immediately after a c indi‐
       cation.  When the contents of two files are identical, the contents  of
       the lower-numbered file is suppressed.

       Under  the  -e  option, diff3 publishes a script for the editor ed that
       will incorporate into file1 all changes between file2 and  file3,  i.e.
       the  changes  that normally would be flagged ==== and ====3.  Option -x
       (-3) produces  a  script  to  incorporate  only  changes  flagged  ====
       (====3).   The  following  command  will  apply the resulting script to

                (cat script; echo '1,$p') ⎪ ed - file1



       Text lines that consist of a single `.' will defeat -e.
       Files longer than 64K bytes won't work.