/sys$common/syshlp/helplib.hlb CMS, MODIFY, CLASS, Restrictions  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    o  You cannot modify a class that has read-only access. If a
       class has read-only access, you must change it to NOREAD_
       ONLY access to change the contents of the class or any other
       characteristics.

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