A code used in a system, such as a communications, computer, automatic data processing, information, or control system, to provide protection against improper or unauthorized use of components in the system, such as storage units, files, input-output channels, communications channels, switching systems, links, or loops. See also  automatic data processing system,  code,  communications,  communications system,  computer system,  control system,  channel,  code,  component,  file,  information system,  input-output channel,  link,  lock,  loop,  protection,  storage unit,  switch,  switching.