diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/server/business/bo/datasetlister/ExternalDataManagementSystemRecord.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/server/business/bo/datasetlister/ExternalDataManagementSystemRecord.java
index c409ab8cc8ffb90099a2972983f256d416671cdb..1f28d69dac46ed77e54e2d0a6f7a759b45490f71 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/server/business/bo/datasetlister/ExternalDataManagementSystemRecord.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/server/business/bo/datasetlister/ExternalDataManagementSystemRecord.java
@@ -16,13 +16,11 @@
 
 package ch.systemsx.cisd.openbis.generic.server.business.bo.datasetlister;
 
-import ch.rinn.restrictions.Private;
 import ch.systemsx.cisd.openbis.generic.server.business.bo.common.CodeRecord;
 
 /**
  * @author Pawel Glyzewski
  */
-@Private
 public class ExternalDataManagementSystemRecord extends CodeRecord
 {
     public String label;
diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/ExternalData.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/ExternalData.java
index 4bd71f8cf48b175772312426e46c70cc64fd429a..508de2b8c91b9ce8595306486f6b8fd541e83437 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/ExternalData.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/ExternalData.java
@@ -100,6 +100,14 @@ public abstract class ExternalData extends CodeWithRegistrationAndModificationDa
         return false; // overriden in subclasses
     }
 
+    /**
+     * @return true if this is a link data set.
+     */
+    public boolean isLinkData()
+    {
+        return false; // overriden in subclasses
+    }
+
     /**
      * @return true if this is a place holder data set.
      */
diff --git a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/LinkDataSet.java b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/LinkDataSet.java
index 769e31e3643229fb2397a0920b256cad3d08e836..e1bac0cb1637c8c3c73391f9aed076e8fe2ca829 100644
--- a/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/LinkDataSet.java
+++ b/openbis/source/java/ch/systemsx/cisd/openbis/generic/shared/basic/dto/LinkDataSet.java
@@ -51,6 +51,12 @@ public class LinkDataSet extends ExternalData
         this.externalCode = externalCode;
     }
 
+    @Override
+    public boolean isLinkData()
+    {
+        return true; // overriden in subclasses
+    }
+
     @Override
     public LinkDataSet tryGetAsLinkDataSet()
     {