diff --git a/src/schema/common.rnc b/src/schema/common.rnc
index 8da894f026302f2b43e4a86c3ee14e9f05e1efd4..079213b58d900f9fa836e668bccb59bf7b42c30c 100644
--- a/src/schema/common.rnc
+++ b/src/schema/common.rnc
@@ -34,6 +34,7 @@ optionalMetadata =
  & element dct:creator { Agent }*
  & element dct:description { rdfLiteral }*
  & element dct:title { rdfLiteral }*
+ & element dct:relation { rdfResource }*
 
 requiredMetadata =
    element dct:publisher { Agent }