/sys$common/syshlp/helplib.hlb CMS, DIFFERENCES, file, Qualifiers, /SENTINEL=("begin-delimiter", "end-delimiter")  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Specifies a pair of strings used to delimit a section of text to
    be ignored during the comparison of both files. The delimiters
    can be up to 256 characters per line, and must be unique. Any text
    between and including the delimiters is treated as if it did not
    exist. If you do not enclose the sentinel strings in quotation
    marks, they are converted to uppercase before the comparison of
    the files. Sentinel strings may contain any characters, but if you
    include spaces or tabs, they must be enclosed in quotation marks.

    Sentinel strings can appear anywhere in a file. If text delimited
    by a sentinel pair crosses record boundaries, the text after the
    delimited region appears in its own record in the output file; it
    is not appended to the contents of the record in which the begin
    delimiter was found.