-<?xml encoding="ISO-8859-1"?>
-
-<!-- Copyright (C) 2000, HELM Team -->
-<!-- -->
-<!-- This file is part of HELM, an Hypertextual, Electronic -->
-<!-- Library of Mathematics, developed at the Computer Science -->
-<!-- Department, University of Bologna, Italy. -->
-<!-- -->
-<!-- HELM is free software; you can redistribute it and/or -->
-<!-- modify it under the terms of the GNU General Public License -->
-<!-- as published by the Free Software Foundation; either version 2 -->
-<!-- of the License, or (at your option) any later version. -->
-<!-- -->
-<!-- HELM is distributed in the hope that it will be useful, -->
-<!-- but WITHOUT ANY WARRANTY; without even the implied warranty of -->
-<!-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -->
-<!-- GNU General Public License for more details. -->
-<!-- -->
-<!-- You should have received a copy of the GNU General Public License -->
-<!-- along with HELM; if not, write to the Free Software -->
-<!-- Foundation, Inc., 59 Temple Place - Suite 330, Boston, -->
-<!-- MA 02111-1307, USA. -->
-<!-- -->
-<!-- For details, see the HELM World-Wide-Web page, -->
-<!-- http://cs.unibo.it/helm/. -->
-
-<!-- DTD for backward pointers metadata. For every object, it lists -->
-<!-- all the other objects directly depending on it. -->
-
-<!ELEMENT rdf:RDF (h:Object)>
-<!ATTLIST rdf:RDF
- xml:lang CDATA #REQUIRED
- xmlns:rdf CDATA #FIXED "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
- xmlns:h CDATA #FIXED "http://www.cs.unibo.it/helm/schemas/mattone.rdf#">
-
-<!ELEMENT h:Object (h:backPointer)*>
-<!ATTLIST h:Object
- rdf:about CDATA #REQUIRED>
-
-<!ELEMENT h:backPointer (h:Occurrence)>
-
-<!ELEMENT h:Occurrence (h:position,h:occurrence)>
-
-<!-- Either MainHypothesis or InHypothesis or InConclusion or -->
-<!-- MainConclusion or InBody. -->
-<!ELEMENT h:position (#PCDATA)>
-
-<!ELEMENT h:occurrence (#PCDATA)>