diff --git a/Gemfile.devel b/Gemfile.devel
deleted file mode 100644
index 71628ca..0000000
--- a/Gemfile.devel
+++ /dev/null
@@ -1,2 +0,0 @@
-gem "isodoc", git: "https://github.com/metanorma/isodoc", branch: "feature/presentation-terms"
-gem "metanorma-standoc", git: "https://github.com/metanorma/metanorma-standoc", branch: "fix/remove-asciimath2unitsml"
diff --git a/lib/metanorma/generic/biblio.rng b/lib/metanorma/generic/biblio.rng
index 71191b2..95a3eb1 100644
--- a/lib/metanorma/generic/biblio.rng
+++ b/lib/metanorma/generic/biblio.rng
@@ -267,11 +267,11 @@ Detailed in https://www.relaton.org/model/creator/</a:documentation>
           <a:documentation>An identifier of the person according to an international identifier scheme</a:documentation>
         </ref>
       </zeroOrMore>
-      <zeroOrMore>
+      <optional>
         <ref name="contact">
           <a:documentation>Contact information for the person, including URI, address, phone number, and email</a:documentation>
         </ref>
-      </zeroOrMore>
+      </optional>
     </element>
   </define>
   <define name="fullname">
@@ -454,11 +454,11 @@ real names (if the person is named with a pseudonym or user name); previous lega
         <a:documentation>An identifier of the organization according to an international identifier scheme</a:documentation>
       </ref>
     </zeroOrMore>
-    <zeroOrMore>
+    <optional>
       <ref name="contact">
         <a:documentation>Contact information for the organization, including address, phone number, and email</a:documentation>
       </ref>
-    </zeroOrMore>
+    </optional>
     <optional>
       <ref name="logo">
         <a:documentation>A logo for the organization</a:documentation>
@@ -540,12 +540,18 @@ real names (if the person is named with a pseudonym or user name); previous lega
   <!-- TODO may change -->
   <define name="contact">
     <a:documentation>Contact information for a person or organization</a:documentation>
-    <choice>
+    <zeroOrMore>
       <ref name="address"/>
+    </zeroOrMore>
+    <zeroOrMore>
       <ref name="phone"/>
+    </zeroOrMore>
+    <zeroOrMore>
       <ref name="email"/>
+    </zeroOrMore>
+    <zeroOrMore>
       <ref name="uri"/>
-    </choice>
+    </zeroOrMore>
   </define>
   <define name="phone">
     <a:documentation>The phone number associated with a person or organization</a:documentation>
@@ -1271,17 +1277,17 @@ for which this claim of validity is made, if applicable</a:documentation>
   </define>
   <define name="validityBegins">
     <element name="validityBegins">
-      <ref name="ISO8601DateTime"/>
+      <ref name="ISO8601Date"/>
     </element>
   </define>
   <define name="validityEnds">
     <element name="validityEnds">
-      <ref name="ISO8601DateTime"/>
+      <ref name="ISO8601Date"/>
     </element>
   </define>
   <define name="validityRevision">
     <element name="revision">
-      <ref name="ISO8601DateTime"/>
+      <ref name="ISO8601Date"/>
     </element>
   </define>
   <define name="TypedTitleString">