--- a/RelaxNG/publidoc.rng	dim. oct. 23 16:45:12 2011 +0200
+++ b/RelaxNG/publidoc.rng	dim. oct. 23 18:05:46 2011 +0200
@@ -986,7 +986,10 @@
   </define>
   <define name="image.type">
     <attribute name="type">
-      <value>thumbnail</value>
+      <choice>
+        <value>cover</value>
+        <value>thumbnail</value>
+      </choice>
     </attribute>
   </define>
   <define name="image.content">