diff --git a/generator/mavschema.xsd b/generator/mavschema.xsd
index 97372ef9dc21d449ab580c6b7601ed97cac3350a..b00f3967ff1f183b47f4a91479574140ee00392b 100644
--- a/generator/mavschema.xsd
+++ b/generator/mavschema.xsd
@@ -208,6 +208,7 @@
         <xs:sequence>
             <xs:element ref="description" minOccurs="0"/>
         </xs:sequence>
+        <xs:attribute ref="since" />
     </xs:complexType>
 </xs:element>