Library /sys$common/syshlp/dtm$dw_helplib.hlb terms, acl  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  A OpenVMS System protection scheme that grants or
  denies access to files based on a list of users. With
  ACLs, you can specify access for a set of users who are
  not in the same UIC group. See also User identification
  code (UIC).