(input)
           A list defining the "what" portion of the authorization being
           requested.

           If the list is of type CSSM_LIST_TYPE_SEXPR, then the list
           presents an authorization request in SPKI format. If a
           specific authorization is being requested, then this input is
           a two-element SEXPR list containing (tag <req>).  The valid
           values for <req> are application-specific. If this is a request
           to derive all possible authorizations based on the
           BaseAuthorizations, Credentials, and Requestors, then this
           input value must be the two-element list containing (tag (*)).
           This list corresponds to "all authorizations". With this input,
           the function tests the provided ACL and certificates against
           the Requestors (and possibly RequestedAuthorizationPeriod) to
           yield all authorizations for which the provided Exhibits
           qualify.