VMS Help CMS, INSERT, GROUP, Description  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The INSERT GROUP command inserts one or more groups into one
    or more other groups. Both groups must exist. When you use the
    INSERT GROUP command to insert group A into group B, the elements
    accessible through group B change as the contents of group A
    change. A group cannot be a member of itself; that is, it cannot
    be a subgroup of itself. For example, you cannot insert group A
    into group B if group A already contains group B.