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

    o  You cannot change the attributes of a group that has been set
       to READ_ONLY. If a group has read-only access, you must change
       it to NOREAD_ONLY to change any other characteristics.

    o  You must specify one or more of the following qualifiers:
       /NAME, /[NO]READ_ONLY, or /REMARK.