(*
    ||M||  This file is part of HELM, an Hypertextual, Electronic        
    ||A||  Library of Mathematics, developed at the Computer Science     
    ||T||  Department, University of Bologna, Italy.                     
    ||I||                                                                
    ||T||  HELM is free software; you can redistribute it and/or         
    ||A||  modify it under the terms of the GNU General Public License   
    \   /  version 2 or (at your option) any later version.              
     \ /   This software is distributed as is, NO WARRANTY.              
      V_______________________________________________________________ *)

type uri = NUri.uri
type id = Aut.id

type bind = Abst | Abbr (* abstraction, abbreviation *)

type term = Sort of int                     (* hierarchy index *)
          | LRef of int                     (* reverse de Bruijn index *)
	  | GRef of uri                     (* reference *)
	  | Cast of term * term             (* type, term *)
	  | Appl of term * term             (* argument, function *)
	  | Bind of id * bind * term * term (* name, binder, content, scope *)

type obj = bind * term (* binder, contents *)

type item = (obj * uri) option (* uri, object *)