Saw this was documented but not implemented....
http://scompall.nocandysw.com/cffi/implicit-defbitfield-values.darcs.patch
Thu May 11 02:21:06 CDT 2006 Stephen Compall scompall@nocandysw.com * implicit defbitfield symbol values
- Foreign Type Translators: defctype does not create Lisp types; you have to use eql specializers. - enum.lisp: Use reduce in %foreign-bitfield-value. Code a default rule for bitfield symbol values.