VMS Help SET, DIRECTORY, Qualifiers, /MODIFIED  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Modifies the time value specified with the /BEFORE or the /SINCE
    qualifier. The /MODIFIED qualifier selects directories according
    to the dates on which they were last modified. This qualifier is
    incompatible with the /BACKUP, /CREATED, and /EXPIRED qualifiers,
    which also allow you to select directories according to time
    attributes. If you specify none of these four time modifiers, the
    default is the /CREATED qualifier.