+ ;; also the CAR of NIL-as-end-of-list
+ (value :init :unbound :ref-known (flushable) :ref-trans symbol-global-value)
+ ;; also the CDR of NIL-as-end-of-list. Its reffer needs special
+ ;; care for this reason, as hash values must be fixnums.
+ (hash :set-trans %set-symbol-hash)