VMS Help SCA, SCA Topics, Glossary, appearance  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    One of the attributes of an occurrence. It tells you whether the
    name of the occurrence is visible or hidden. You can instruct SCA
    to show only occurrences with a particular appearance by using the
    "occurrence=" attribute selection. For example, you can ask for
    hidden occurrences by specifying "occurrence=hidden."