diff --git a/dtd/align.owl b/dtd/align.owl
index b3d292f256744783865f7e6fa6015bef6d1c6234..631ba54a43e1bb278fc0ca672662fa130d5208d3 100644
--- a/dtd/align.owl
+++ b/dtd/align.owl
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8" ?>
 <!-- $Id$
  !
- ! Copyright (C) 2003-2004 INRIA Rhône-Alpes.
+ ! Copyright (C) 2003-2004, 2006 INRIA Rhône-Alpes.
  !
  ! This program is free software; you can redistribute it and/or
  ! modify it under the terms of the GNU Lesser General Public License
@@ -21,7 +21,7 @@
 <rdf:RDF xmlns:dc="http://purl.org/dc/elements/1.1/"
     xmlns:owl="http://www.w3.org/2002/07/owl#"
     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
-    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" 
+    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
     xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
     xml:base="http://knowledgeweb.semanticweb.org/heterogeneity/alignment"
     xmlns="http://knowledgeweb.semanticweb.org/heterogeneity/alignment">
@@ -35,95 +35,113 @@
 
 <owl:DatatypeProperty rdf:ID="xml">
   <rdfs:domain rdf:resource="#Alignment"/>
-  <rdf:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
+  <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
 </owl:DatatypeProperty>
 
-<owl:DatatypeProperty rdf:ID="#onto1">
+<owl:DatatypeProperty rdf:ID="onto1">
   <rdfs:comment>This string is the URl at whitch the ontology can be fetched</rdfs:comment>
   <rdfs:domain rdf:resource="Alignment"/>
-  <rdf:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
+  <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
 </owl:DatatypeProperty>
 
-<owl:DatatypeProperty rdf:ID="#onto2">
+<owl:DatatypeProperty rdf:ID="onto2">
   <rdfs:comment>This string is the URl at whitch the ontology can be fetched</rdfs:comment>
   <rdfs:domain rdf:resource="Alignment"/>
-  <rdf:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
+  <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
 </owl:DatatypeProperty>
 
 <owl:DatatypeProperty rdf:ID="type">
   <rdfs:comment>This is indeed a 2 letter string on the alphabet 1 ? + *</rdfs:comment>
   <rdfs:domain rdf:resource="#Alignment"/>
-  <rdf:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
+  <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
 </owl:DatatypeProperty>
 
 <owl:ObjectProperty rdf:ID="map">
   <rdfs:domain rdf:resource="#Alignment"/>
-  <rdf:range rdf:resource="#Cell"/>
+  <rdfs:range rdf:resource="#Cell"/>
 </owl:ObjectProperty>
 
 <owl:DatatypeProperty rdf:ID="measure">
   <rdfs:domain rdf:resource="#Cell"/>
-  <rdf:range rdf:resource="http://www.w3.org/2001/XMLSchema#float"/>
+  <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#float"/>
 </owl:DatatypeProperty>
 
 <owl:DatatypeProperty rdf:ID="relation">
   <rdfs:comment>This is currently a string but should be upgraded soon</rdfs:comment>
   <rdfs:domain rdf:resource="#Cell"/>
-  <rdf:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
+  <rdfs:range rdf:resource="http://www.w3.org/2001/XMLSchema#string"/>
 </owl:DatatypeProperty>
 
 <owl:ObjectProperty rdf:ID="entity1">
   <rdfs:domain rdf:resource="#Cell"/>
-  <rdf:range rdf:resource="#OWLEntity"/>
+  <rdfs:range rdf:resource="#OWLEntity"/>
 </owl:ObjectProperty>
 
 <owl:ObjectProperty rdf:ID="entity2">
   <rdfs:domain rdf:resource="#Cell"/>
-  <rdf:range rdf:resource="#OWLEntity"/>
+  <rdfs:range rdf:resource="#OWLEntity"/>
 </owl:ObjectProperty>
 
 <!-- Then define three classes which specify the cardinality of properties -->
 
 <owl:Class rdf:ID="Alignment">
-  <owl:Restriction>
-    <owl:onProperty rdf:resource="#xml" />
-    <owl:cardinality>1</owl:cardinality>
-  </owl:Restriction>
-  <owl:Restriction>
-    <owl:onProperty rdf:resource="#onto1" />
-    <owl:cardinality>1</owl:cardinality>
-  </owl:Restriction>
-  <owl:Restriction>
-    <owl:onProperty rdf:resource="#onto2" />
-    <owl:cardinality>1</owl:cardinality>
-  </owl:Restriction>
-  <owl:Restriction>
-    <owl:onProperty rdf:resource="#type" />
-    <owl:cardinality>1</owl:cardinality>
-  </owl:Restriction>
-  <owl:Restriction>
-    <owl:onProperty rdf:resource="#map" />
-    <owl:allValuesFrom rdf:resource="#Cell" />
-  </owl:Restriction>
+  <rdfs:subClassOf>
+    <owl:Restriction>
+      <owl:onProperty rdf:resource="#xml" />
+      <owl:cardinality>1</owl:cardinality>
+    </owl:Restriction>
+  </rdfs:subClassOf>
+  <rdfs:subClassOf>
+    <owl:Restriction>
+      <owl:onProperty rdf:resource="#onto1" />
+      <owl:cardinality>1</owl:cardinality>
+    </owl:Restriction>
+  </rdfs:subClassOf>
+  <rdfs:subClassOf>
+    <owl:Restriction>
+      <owl:onProperty rdf:resource="#onto2" />
+      <owl:cardinality>1</owl:cardinality>
+    </owl:Restriction>
+  </rdfs:subClassOf>
+  <rdfs:subClassOf>
+    <owl:Restriction>
+      <owl:onProperty rdf:resource="#type" />
+      <owl:cardinality>1</owl:cardinality>
+    </owl:Restriction>
+  </rdfs:subClassOf>
+  <rdfs:subClassOf>
+    <owl:Restriction>
+      <owl:onProperty rdf:resource="#map" />
+      <owl:allValuesFrom rdf:resource="#Cell" />
+    </owl:Restriction>
+  </rdfs:subClassOf>
 </owl:Class>
 
 <owl:Class rdf:ID="Cell">
-  <owl:Restriction>
-    <owl:onProperty rdf:resource="#entity1" />
-    <owl:cardinality>1</owl:cardinality>
-  </owl:Restriction>
-  <owl:Restriction>
-    <owl:onProperty rdf:resource="#entity2" />
-    <owl:cardinality>1</owl:cardinality>
-  </owl:Restriction>
-  <owl:Restriction>
-    <owl:onProperty rdf:resource="#measure" />
-    <owl:cardinality>1</owl:cardinality>
-  </owl:Restriction>
-  <owl:Restriction>
-    <owl:onProperty rdf:resource="#relation" />
-    <owl:cardinality>1</owl:cardinality>
-  </owl:Restriction>
+  <rdfs:subClassOf>
+    <owl:Restriction>
+      <owl:onProperty rdf:resource="#entity1" />
+      <owl:cardinality>1</owl:cardinality>
+    </owl:Restriction>
+  </rdfs:subClassOf>
+  <rdfs:subClassOf>
+    <owl:Restriction>
+      <owl:onProperty rdf:resource="#entity2" />
+      <owl:cardinality>1</owl:cardinality>
+    </owl:Restriction>
+  </rdfs:subClassOf>
+  <rdfs:subClassOf>
+    <owl:Restriction>
+      <owl:onProperty rdf:resource="#measure" />
+      <owl:cardinality>1</owl:cardinality>
+    </owl:Restriction>
+  </rdfs:subClassOf>
+  <rdfs:subClassOf>
+    <owl:Restriction>
+      <owl:onProperty rdf:resource="#relation" />
+      <owl:cardinality>1</owl:cardinality>
+    </owl:Restriction>
+  </rdfs:subClassOf>
 </owl:Class>
 
 <!--
diff --git a/dtd/align.rdfs b/dtd/align.rdfs
index 79fab5c3974dbfabe17114da707d36ec2c1c3cec..f8ba74d6f05632a41ff665e239c9d66670138ad7 100644
--- a/dtd/align.rdfs
+++ b/dtd/align.rdfs
@@ -2,10 +2,11 @@
 <!DOCTYPE rdf:RDF [
 	 <!ENTITY rdf 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
 	 <!ENTITY alignment 'http://knowledgeweb.semanticweb.org/heterogeneity/alignment'>
-	 <!ENTITY rdfs 'http://www.w3.org/TR/1999/PR-rdf-schema-19990303#'>
+	 <!ENTITY rdfs 'http://www.w3.org/2000/01/rdf-schema#'>
 ]>
 
 <!-- Contributed by Natasha Noy, 2004 -->
+<!-- improved by Antoine Isaac -->
 <!-- $Id$ -->
 
 <rdf:RDF xmlns:rdf="&rdf;"