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

    /WORD_MATCH=INITIAL_SUBSTRING (default)
    /WORD_MATCH=WHOLE_WORD

    /WORD_MATCH=INITIAL_SUBSTRING matches all words that begin with
    a word specified in the search string. The search string can
    contain multiple words to be matched. Only messages that match
    every word in the search string (in any order) are output.

    /WORD_MATCH=WHOLE_WORD matches whole words only and refines your
    search to the exact words specified. For example, an exact search
    on ACC screens out dozens of other messages containing words that
    begin with the letters ACC.