The immedate types are the basic types used by the FLI to convert between Lisp and a foreign language.
The immediate types of the FLI are :boolean, :byte, :char, :const, :double, :enum, :float, :int, :lisp-double-float, :lisp-float, :lisp-single-float, :long, :pointer, :short, :signed and :unsigned. For details on each immediate type, see the relevant reference entry.