Choose the Set ACL... menu item to manipulate the access
  control list (ACL) on various objects in the library. An
  ACL consists of access control entries (ACEs) that grant
  or deny access to a command or other object to specified
  users.

  Generally, there are two ways in which you can use ACLs
  on objects:

      o  To control and restrict access to commands

         For example, you can create an ACL specifying
         certain users who are not allowed to use certain
         commands, or other users who are allowed to use
         only certain commands.

      o  To control and restrict access to other objects
         (elements, groups, classes, the element list,
         the group list, the class list, library history,
         and library attributes)

         For example, you can create an ACL specifying
         certain users who are not allowed to insert or
         modify a particular element.

  When there is no ACL on a command or other object, access
  to the command or other object is unrestricted.
  Assigning an ACL to an object limits access strictly to
  the specified user or users.

  The use of ACLs could possibly cause unintended
  restrictions. You should fully understand the composition
  of both OpenVMS and CMS ACLs before using CMS ACLs. See the
  "Guide to DIGITAL Code Management System for OpenVMS
  Systems" for more information on using ACLs.