diff --git a/src/fr/inrialpes/exmo/align/impl/BasicAlignment.java b/src/fr/inrialpes/exmo/align/impl/BasicAlignment.java
index 9bf486c091ec21e10ef9d8d12a9afe4b8bb2d19f..c61799b1ccff57f526b8374a8c675bc37fb26b7c 100644
--- a/src/fr/inrialpes/exmo/align/impl/BasicAlignment.java
+++ b/src/fr/inrialpes/exmo/align/impl/BasicAlignment.java
@@ -86,7 +86,7 @@ public class BasicAlignment implements Alignment {
 	hash2 = new Hashtable<Object,Set<Cell>>();
 	extensions = new BasicParameters();
 	namespaces = new BasicParameters();
-	if ( this instanceof AlignmentProcess ) setExtension( Annotations.ALIGNNS, Annotations.METHOD, getClass().getName() );
+	if ( this instanceof AlignmentProcess ) setExtension( Namespace.ALIGNMENT.uri, Annotations.METHOD, getClass().getName() );
 	onto1 = new BasicOntology<Object>();
 	onto2 = new BasicOntology<Object>();
     }
@@ -641,18 +641,18 @@ public class BasicAlignment implements Alignment {
 	for ( Object ext : ((BasicParameters)extensions).getValues() ){
 	    result.setExtension( ((String[])ext)[0], ((String[])ext)[1], ((String[])ext)[2] );
 	}
-	String oldid = result.getExtension( Annotations.ALIGNNS, Annotations.ID );
+	String oldid = result.getExtension( Namespace.ALIGNMENT.uri, Annotations.ID );
 	if ( oldid != null && !oldid.equals("") ) {
-	    result.setExtension( Annotations.ALIGNNS, Annotations.DERIVEDFROM, oldid );
-	    result.getExtensions().unsetParameter( Annotations.ALIGNNS+Annotations.ID );
+	    result.setExtension( Namespace.ALIGNMENT.uri, Annotations.DERIVEDFROM, oldid );
+	    result.getExtensions().unsetParameter( Namespace.ALIGNMENT.uri+Annotations.ID );
 	}
-	String pretty = result.getExtension( Annotations.ALIGNNS, Annotations.PRETTY );
+	String pretty = result.getExtension( Namespace.ALIGNMENT.uri, Annotations.PRETTY );
 	if ( pretty != null ){
-	    result.setExtension( Annotations.ALIGNNS, Annotations.PRETTY, pretty+"/inverted" );
+	    result.setExtension( Namespace.ALIGNMENT.uri, Annotations.PRETTY, pretty+"/inverted" );
 	};
-	result.setExtension( Annotations.ALIGNNS, Annotations.PROVENANCE,
-			     result.getExtension( Annotations.ALIGNNS, Annotations.PROVENANCE )+"" );
-	result.setExtension( Annotations.ALIGNNS, Annotations.METHOD, "http://exmo.inrialpes.fr/align/impl/BasicAlignment#inverse" );
+	result.setExtension( Namespace.ALIGNMENT.uri, Annotations.PROVENANCE,
+			     result.getExtension( Namespace.ALIGNMENT.uri, Annotations.PROVENANCE )+"" );
+	result.setExtension( Namespace.ALIGNMENT.uri, Annotations.METHOD, "http://exmo.inrialpes.fr/align/impl/BasicAlignment#inverse" );
 	for ( Enumeration e = namespaces.getNames() ; e.hasMoreElements(); ){
 	    String label = (String)e.nextElement();
 	    result.setXNamespace( label, getXNamespace( label ) );
@@ -695,12 +695,12 @@ public class BasicAlignment implements Alignment {
 	for ( Object ext : ((BasicParameters)extensions).getValues() ){
 	    align.setExtension( ((String[])ext)[0], ((String[])ext)[1], ((String[])ext)[2] );
 	}
-	String oldid = align.getExtension( Annotations.ALIGNNS, Annotations.ID );
+	String oldid = align.getExtension( Namespace.ALIGNMENT.uri, Annotations.ID );
 	if ( oldid != null && !oldid.equals("") ) {
-	    align.setExtension( Annotations.ALIGNNS, Annotations.DERIVEDFROM, oldid );
-	    align.getExtensions().unsetParameter( Annotations.ALIGNNS+Annotations.ID );
+	    align.setExtension( Namespace.ALIGNMENT.uri, Annotations.DERIVEDFROM, oldid );
+	    align.getExtensions().unsetParameter( Namespace.ALIGNMENT.getUriPrefix()+Annotations.ID );
 	}
-	align.setExtension( Annotations.ALIGNNS, Annotations.METHOD, this.getClass().getName()+"#clone" );
+	align.setExtension( Namespace.ALIGNMENT.uri, Annotations.METHOD, this.getClass().getName()+"#clone" );
 	for ( Enumeration e = namespaces.getNames() ; e.hasMoreElements(); ){
 	    String label = (String)e.nextElement();
 	    align.setXNamespace( label, getXNamespace( label ) );
diff --git a/src/fr/inrialpes/exmo/align/impl/BasicCell.java b/src/fr/inrialpes/exmo/align/impl/BasicCell.java
index 90f3eb1e809bc0f5face7a8ca0872daf37b7237b..32eba83cc9df0316b9fa53841981a6c7e4661ea9 100644
--- a/src/fr/inrialpes/exmo/align/impl/BasicCell.java
+++ b/src/fr/inrialpes/exmo/align/impl/BasicCell.java
@@ -164,7 +164,7 @@ public class BasicCell implements Cell, Comparable<Cell> {
 	    for ( Object ext : ((BasicParameters)extensions).getValues() ){
 		result.setExtension( ((String[])ext)[0], ((String[])ext)[1], ((String[])ext)[2] );
 	    }
-	    result.getExtensions().unsetParameter( Annotations.ALIGNNS+Annotations.ID );
+	    result.getExtensions().unsetParameter( Namespace.ALIGNMENT.getUriPrefix()+Annotations.ID );
 	}
 	// The sae should be done for the measure
 	return result;
diff --git a/src/fr/inrialpes/exmo/align/impl/ObjectCell.java b/src/fr/inrialpes/exmo/align/impl/ObjectCell.java
index 22dd5e89ef9f7aabaac6e86be451044feda07f8e..c334748edde9331a192e297db68402104a447f0e 100644
--- a/src/fr/inrialpes/exmo/align/impl/ObjectCell.java
+++ b/src/fr/inrialpes/exmo/align/impl/ObjectCell.java
@@ -108,7 +108,7 @@ public class ObjectCell extends BasicCell {
 	    for ( Object ext : ((BasicParameters)extensions).getValues() ){
 		result.setExtension( ((String[])ext)[0], ((String[])ext)[1], ((String[])ext)[2] );
 	    }
-	    result.getExtensions().unsetParameter( Annotations.ALIGNNS+Annotations.ID );
+	    result.getExtensions().unsetParameter( Namespace.ALIGNMENT.getUriPrefix()+Annotations.ID );
 	}
 	// The sae should be done for the measure
 	return result;
diff --git a/src/fr/inrialpes/exmo/align/impl/eval/PRecEvaluator.java b/src/fr/inrialpes/exmo/align/impl/eval/PRecEvaluator.java
index 6bb964db111a981a44294d9dc385cc77b3ad6d16..48817f2449084a26e56e0b81e881071396a7a041 100644
--- a/src/fr/inrialpes/exmo/align/impl/eval/PRecEvaluator.java
+++ b/src/fr/inrialpes/exmo/align/impl/eval/PRecEvaluator.java
@@ -29,6 +29,7 @@ import org.semanticweb.owl.align.Evaluator;
 import fr.inrialpes.exmo.align.impl.BasicEvaluator;
 import fr.inrialpes.exmo.align.impl.BasicAlignment;
 import fr.inrialpes.exmo.align.impl.Annotations;
+import fr.inrialpes.exmo.align.impl.Namespace;
 
 import java.util.Enumeration;
 import java.util.Iterator;
@@ -139,7 +140,7 @@ public class PRecEvaluator extends BasicEvaluator implements Evaluator {
 	fmeasure = 2 * precision * recall / (precision + recall);
 	overall = recall * (2 - (1 / precision));
 	result = recall / precision;
-	String timeExt = align2.getExtension( Annotations.ALIGNNS, Annotations.TIME );
+	String timeExt = align2.getExtension( Namespace.ALIGNMENT.uri, Annotations.TIME );
 	if ( timeExt != null ) time = Long.parseLong(timeExt);
 	//System.err.println(">>>> " + nbcorrect + " : " + nbfound + " : " + nbexpected);
 	return (result);