The RCS output format is designed specifically for use by the Revision
Control System, which is a set of free programs used for organizing
different versions and systems of files. Use the `-n' or
`--rcs' option to select this output format. It is like the
forward ed format (see section Forward ed Scripts), but it can represent
arbitrary changes to the contents of a file because it avoids the
forward ed format's problems with lines consisting of a single
period and with incomplete lines. Instead of ending text sections with
a line consisting of a single period, each command specifies the number
of lines it affects; a combination of the `a' and `d'
commands are used instead of `c'. Also, if the second file ends
in a changed incomplete line, then the output also ends in an
incomplete line.
Here is the output of `diff -n lao tzu' (see section Two Sample Input Files, for the complete contents of the two files):
d1 2 d4 1 a4 2 The named is the mother of all things. a11 3 They both may be called deep and profound. Deeper and more profound, The door of all subtleties!