lib/asciidoctor/gb/biblio.rng in asciidoctor-gb-0.2.3 vs lib/asciidoctor/gb/biblio.rng in asciidoctor-gb-0.2.4

@@ -440,13 +440,13 @@
       <ref name="abstract"/>
     </optional>
     <optional>
       <ref name="status"/>
     </optional>
-    <optional>
+    <zeroOrMore>
       <ref name="copyright"/>
-    </optional>
+    </zeroOrMore>
     <zeroOrMore>
       <ref name="docrelation"/>
     </zeroOrMore>
   </define>
   <define name="btitle">
@@ -487,14 +487,19 @@
           <value>confirmed</value>
           <value>updated</value>
           <value>issued</value>
         </choice>
       </attribute>
-      <ref name="bfrom"/>
-      <optional>
-        <ref name="bto"/>
-      </optional>
+      <choice>
+        <group>
+          <ref name="bfrom"/>
+          <optional>
+            <ref name="bto"/>
+          </optional>
+        </group>
+        <ref name="date_on"/>
+      </choice>
     </element>
   </define>
   <define name="bfrom">
     <element name="from">
       <choice>
@@ -503,9 +508,17 @@
       </choice>
     </element>
   </define>
   <define name="bto">
     <element name="to">
+      <choice>
+        <data type="gYear"/>
+        <data type="date"/>
+      </choice>
+    </element>
+  </define>
+  <define name="date_on">
+    <element name="on">
       <choice>
         <data type="gYear"/>
         <data type="date"/>
       </choice>
     </element>