diff --git a/src/main/java/eu/dnetlib/dhp/schema/common/ModelConstants.java b/src/main/java/eu/dnetlib/dhp/schema/common/ModelConstants.java
index ac95d86..e9261dc 100644
--- a/src/main/java/eu/dnetlib/dhp/schema/common/ModelConstants.java
+++ b/src/main/java/eu/dnetlib/dhp/schema/common/ModelConstants.java
@@ -47,9 +47,9 @@ public class ModelConstants {
 	public static final String DNET_REVIEW_LEVELS = "dnet:review_levels";
 	public static final String DNET_PROGRAMMING_LANGUAGES = "dnet:programming_languages";
 	public static final String DNET_EXTERNAL_REFERENCE_TYPE = "dnet:externalReference_typologies";
-	public static final String DNET_RELATIONS_RELTYPE = "dnet:relation_relType";
-	public static final String DNET_RELATIONS_SUBRELTYPE = "dnet:relation_subRelType";
-	public static final String DNET_RELATIONS_RELCLASS = "dnet:relation_relClass";
+	public static final String DNET_RELATION_RELTYPE = "dnet:relation_relType";
+	public static final String DNET_RELATION_SUBRELTYPE = "dnet:relation_subRelType";
+	public static final String DNET_RELATION_RELCLASS = "dnet:relation_relClass";
 
 	public static final String SYSIMPORT_CROSSWALK_REPOSITORY = "sysimport:crosswalk:repository";
 	public static final String SYSIMPORT_CROSSWALK_ENTITYREGISTRY = "sysimport:crosswalk:entityregistry";