diff --git a/Gemfile.devel b/Gemfile.devel
new file mode 100644
index 0000000..e3a37c0
--- /dev/null
+++ b/Gemfile.devel
@@ -0,0 +1 @@
+gem "isodoc", git: "https://github.com/metanorma/isodoc", branch: "fix/i18n-yaml-inheritance"
diff --git a/lib/isodoc/ietf/i18n.rb b/lib/isodoc/ietf/i18n.rb
index 3912940..90693ab 100644
--- a/lib/isodoc/ietf/i18n.rb
+++ b/lib/isodoc/ietf/i18n.rb
@@ -1,13 +1,14 @@
 module IsoDoc
   module Ietf
     class I18n < IsoDoc::I18n
-       def load_yaml1(lang, script)
-        y = if lang == "en"
-              YAML.load_file(File.join(File.dirname(__FILE__), "i18n-en.yaml"))
-            else
-              YAML.load_file(File.join(File.dirname(__FILE__), "i18n-en.yaml"))
-            end
-        super.deep_merge(y)
+      def load_file(fname)
+        f = File.join(File.dirname(__FILE__), fname)
+        File.exist?(f) ? YAML.load_file(f) : {}
+      end
+
+      def load_yaml1(lang, script)
+        y = load_file("i18n-#{yaml_lang(lang, script)}.yaml")
+        y.empty? ? load_file("i18n-en.yaml").merge(super) : super.deep_merge(y)
       end
     end
   end
diff --git a/lib/metanorma/ietf/biblio.rng b/lib/metanorma/ietf/biblio.rng
index 398a4ae..357f879 100644
--- a/lib/metanorma/ietf/biblio.rng
+++ b/lib/metanorma/ietf/biblio.rng
@@ -374,6 +374,16 @@
       <ref name="image"/>
     </element>
   </define>
+  <define name="depiction">
+    <element name="depiction">
+      <optional>
+        <attribute name="scope"/>
+      </optional>
+      <zeroOrMore>
+        <ref name="image"/>
+      </zeroOrMore>
+    </element>
+  </define>
   <define name="NameWithVariants">
     <element name="primary">
       <ref name="LocalizedString"/>
@@ -760,6 +770,9 @@
     <optional>
       <ref name="validity"/>
     </optional>
+    <optional>
+      <ref name="depiction"/>
+    </optional>
   </define>
   <define name="ReducedBibliographicItem">
     <optional>