VMS Help CMS, DIFFERENCES, file, Qualifiers, /PARALLEL  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Controls whether the differing lines from the two files are
    formatted side by side. If you specify /PARALLEL, the differences
    from the first file are displayed on the left and the differences
    from the second file are displayed on the right. The heading of
    the differences report displays the file specification of the
    first file on the left and the file specification of the second
    file on the right.

    By default, the width of the listing is 132. Use the /WIDTH
    qualifier to control the width. Vertical lines separate the text
    on the left side of the report from the text on the right side.
    The text from each of the files is allotted equal space (half the
    width of the full report).

    If a line from one of the files being compared is longer than half
    the width of the full report, the line is truncated on the right.
    A plus sign (+) is printed at the end of the line to indicate
    that the line has been truncated.