diff --git a/procedures/query/applyBackReference.sql b/procedures/query/applyBackReference.sql
index 3a62957dc5c971315533bf21d4d326e07df1f199..38d8acb95b1020b6d73821098c21e41a88db27d7 100644
--- a/procedures/query/applyBackReference.sql
+++ b/procedures/query/applyBackReference.sql
@@ -113,6 +113,7 @@ BEGIN
                     ')');
             END IF;
         ELSE
+            -- unversioned queries
             IF targetSet IS NULL OR sourceSet = targetSet THEN
                 SET @stmtBackRefStr = CONCAT('DELETE FROM `',
                     sourceSet,