diff --git a/grammars/biblio.rng b/grammars/biblio.rng
index ea06414..86f8275 100644
--- a/grammars/biblio.rng
+++ b/grammars/biblio.rng
@@ -88,7 +88,7 @@
       <text/>
     </element>
   </define>
-  <define name="LocalizedString">
+  <define name="LocalizedString1">
     <optional>
       <!-- multiple languages and scripts possible: comma delimit them if so -->
       <attribute name="language"/>
@@ -98,6 +98,16 @@
     </optional>
     <text/>
   </define>
+  <define name="LocalizedString">
+    <choice>
+      <ref name="LocalizedString1"/>
+      <oneOrMore>
+        <element name="variant">
+          <ref name="LocalizedString1"/>
+        </element>
+      </oneOrMore>
+    </choice>
+  </define>
   <!--
     Unlike UML, change type to format: type is overloaded
     Would be need if plain were default value and could omit the attribute
@@ -121,7 +131,7 @@
     </optional>
     <ref name="LocalizedStringOrXsAny"/>
   </define>
-  <define name="LocalizedStringOrXsAny">
+  <define name="LocalizedStringOrXsAny1">
     <optional>
       <!-- multiple languages and scripts possible: comma delimit them if so -->
       <attribute name="language"/>
@@ -136,6 +146,16 @@
       </choice>
     </oneOrMore>
   </define>
+  <define name="LocalizedStringOrXsAny">
+    <choice>
+      <ref name="LocalizedStringOrXsAny1"/>
+      <oneOrMore>
+        <element name="variant">
+          <ref name="LocalizedStringOrXsAny1"/>
+        </element>
+      </oneOrMore>
+    </choice>
+  </define>
   <define name="contributor">
     <element name="contributor">
       <zeroOrMore>
@@ -641,9 +661,9 @@
     <optional>
       <ref name="status"/>
     </optional>
-    <optional>
+    <zeroOrMore>
       <ref name="copyright"/>
-    </optional>
+    </zeroOrMore>
     <zeroOrMore>
       <ref name="docrelation"/>
     </zeroOrMore>
@@ -1001,7 +1021,17 @@
       <optional>
         <ref name="to"/>
       </optional>
-      <ref name="owner"/>
+      <oneOrMore>
+        <ref name="owner"/>
+      </oneOrMore>
+      <optional>
+        <ref name="copyright_scope"/>
+      </optional>
+    </element>
+  </define>
+  <define name="copyright_scope">
+    <element name="scope">
+      <text/>
     </element>
   </define>
   <define name="from">
diff --git a/grammars/isodoc.rng b/grammars/isodoc.rng
index 9555813..e182d20 100644
--- a/grammars/isodoc.rng
+++ b/grammars/isodoc.rng
@@ -53,6 +53,14 @@
         <optional>
           <attribute name="alt"/>
         </optional>
+        <optional>
+          <attribute name="case">
+            <choice>
+              <value>capital</value>
+              <value>lowercase</value>
+            </choice>
+          </attribute>
+        </optional>
         <text/>
       </element>
     </define>
@@ -902,7 +910,15 @@
       <attribute name="id">
         <data type="ID"/>
       </attribute>
-      <ref name="paragraph"/>
+      <oneOrMore>
+        <choice>
+          <ref name="paragraph"/>
+          <ref name="ul"/>
+          <ref name="ol"/>
+          <ref name="dl"/>
+          <ref name="formula"/>
+        </choice>
+      </oneOrMore>
     </element>
   </define>
   <define name="termexample">
diff --git a/grammars/isostandard.rng b/grammars/isostandard.rng
index 8b2f588..19ae1a7 100644
--- a/grammars/isostandard.rng
+++ b/grammars/isostandard.rng
@@ -91,6 +91,12 @@
     </define>
     <define name="sections">
       <element name="sections">
+        <zeroOrMore>
+          <choice>
+            <ref name="note"/>
+            <ref name="admonition"/>
+          </choice>
+        </zeroOrMore>
         <ref name="clause"/>
         <optional>
           <choice>
@@ -263,6 +269,8 @@
         <value>publicly-available-specification</value>
         <value>international-workshop-agreement</value>
         <value>guide</value>
+        <value>amendment</value>
+        <value>technical-corrigendum</value>
       </choice>
     </define>
     <define name="structuredidentifier">
@@ -510,7 +518,7 @@
         </attribute>
       </optional>
       <oneOrMore>
-        <ref name="paragraph-with-footnote"/>
+        <ref name="BasicBlock"/>
       </oneOrMore>
     </element>
   </define>
diff --git a/lib/relaton_ietf/scrapper.rb b/lib/relaton_ietf/scrapper.rb
index 0e4128e..cca4244 100644
--- a/lib/relaton_ietf/scrapper.rb
+++ b/lib/relaton_ietf/scrapper.rb
@@ -314,6 +314,8 @@ def dates(reference)
         [RelatonBib::BibliographicDate.new(type: "published", on: date)]
       end
 
+      # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
+
       #
       # Extract document identifiers from reference
       #
@@ -337,6 +339,7 @@ def docids(reference, ver)
           RelatonBib::DocumentIdentifier.new(id: id, type: si[:name])
         end.compact
       end
+      # enable Metrics/MethodLength, Metrics/AbcSize
 
       #
       # Extract series form reference
diff --git a/lib/relaton_ietf/version.rb b/lib/relaton_ietf/version.rb
index 515b7fd..25d034f 100644
--- a/lib/relaton_ietf/version.rb
+++ b/lib/relaton_ietf/version.rb
@@ -1,3 +1,3 @@
 module RelatonIetf
-  VERSION = "1.0.4".freeze
+  VERSION = "1.1.0".freeze
 end
diff --git a/relaton_ietf.gemspec b/relaton_ietf.gemspec
index 41efdd4..a6f3994 100644
--- a/relaton_ietf.gemspec
+++ b/relaton_ietf.gemspec
@@ -40,5 +40,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "vcr"
   spec.add_development_dependency "webmock"
 
-  spec.add_dependency "relaton-bib", ">= 1.0.4"
+  spec.add_dependency "relaton-bib", "~> 1.1.0"
 end