diff --git a/CDT-notification.xsd b/CDT-notification.xsd
index 645fc044c0c33b312618436280bc3412316a6b52..cd2c8786926b0ed05229a589227fe6ccaa0ebd01 100644
--- a/CDT-notification.xsd
+++ b/CDT-notification.xsd
@@ -59,7 +59,7 @@ oneM2M EXPRESSLY ADVISES ANY AND ALL USE OF OR RELIANCE UPON THIS INFORMATION PR
                         </xs:element>                      
                     <xs:element name="verificationRequest" type="xs:boolean" minOccurs="0"/>
                     <xs:element name="subscriptionDeletion" type="xs:boolean" minOccurs="0"/>
-                    <xs:element name="subscriptionReference" type="xs:anyURI" minOccurs="0"/>
+                    <xs:element name="subscriptionReference" type="xs:anyURI"/>
                     <xs:element name="creator" type="m2m:ID" minOccurs="0"/>
                     <xs:element name="notificationForwardingURI" type="xs:anyURI" minOccurs="0"/>
                     <xs:element name="notificationTarget" type="m2m:ID" minOccurs="0"/>