;;; Types

sign := *top* &
[ ORTH *diff-list*,
  CATEG cat,
  NUMAGR agr ].

cat := *top*.

s := cat.

np := cat.

vp := cat.

det := cat.

n := cat.

agr := *top*.

sg := agr.

pl := agr.

phrase := sign &
[ ORTH [ LIST #first,
	 LAST #last ],
   ARGS [ FIRST [ ORTH [ LIST #first,
                         LAST #middle ] ], 
          REST [ FIRST [ ORTH [ LIST #middle,
                                LAST #last ]]]]].

word := sign &
[ ORTH [ LIST [ FIRST string,
                REST #end ],
         LAST #end ]].

sg-word := word &
[ NUMAGR sg ].

pl-word := word &
[ NUMAGR pl ].

;;; standard types

string := *top*.

*list* := *top*.

*ne-list* := *list* &
 [ FIRST *top*,
   REST *list* ].

*null* := *list*.

*diff-list* := *top* &
 [ LIST *list*,
   LAST *list* ].