/sys$common/syshlp/helplib.hlb DIFFERENCES, Qualifiers, /IGNORE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /IGNORE=(keyword[,...])

    Inhibits the comparison of the specified characters, strings,
    or records; also controls whether the comparison records are
    output to the listing file as edited records or exactly as they
    appeared in the input file. If you specify only one keyword, you
    can omit the parentheses. The keyword parameter refers to either
    a character or a keyword. The first set of keywords determines
    what, if anything, is ignored during file comparison; the second
    set of keywords determines whether or not ignored characters are
    included in the output. The following keywords are valid options
    for the /IGNORE qualifier:

    Keyword          Item Ignored

    BLANK_LINES      Blank lines between data lines.

    CASE             Case of the text being compared.

    COMMENTS         Data following a comment character. (Use the
                     /COMMENT_DELIMITER qualifier to designate one or
                     more nondefault comment delimiters.)

    FORM_FEEDS       Form feed character.

    HEADER[=n]       First n records of the file, beginning with
                     a record whose first character is a form
                     feed. The first record is not ignored if the
                     only character it contains is a form feed. (N
                     indicates the number of records and defaults
                     to 2. A record with a single form feed is not
                     counted.)

    SPACING          Extra blank spaces or tabs within data lines.

    TRAILING_SPACES  Space and tab characters at the end of a data
                     line.

    Keyword          Status of Ignored Items in Output

    EDITED           Omits ignored characters from the output
                     records.

    EXACT            Includes ignored characters in the output
                     records.

    PRETTY           Formats output records.

    Each data line is checked for COMMENTS, FORM_FEEDS, HEADER,
    and SPACING before it is tested for TRAILING_SPACES and then
    BLANK_LINES. Therefore, if you direct the DIFFERENCES command to
    ignore COMMENTS, TRAILING_SPACES, and BLANK_LINES, it ignores a
    record that contains several spaces or blank lines followed by a
    comment.

    By default, the DIFFERENCES command compares every character
    in each file and reports all differences. Also, by default, the
    DIFFERENCES command lists records in the output file with all
    ignored characters deleted.

    If you specify the /PARALLEL qualifier, output records are
    always formatted. To format output records, specify the following
    characters:

    Character              Formatted Output

    Tab (Ctrl/I)           1-8 spaces
    Return (Ctrl/M)        <CR>
    Line feed (Ctrl/J)     <LF>
    Vertical tab (Ctrl/K)  <VT>
    Form feed (Ctrl/L)     <FF>
    Other nonprinting      . (period)
    characters