--- a/rdf-concepts/index.html	Wed Aug 08 09:46:45 2012 +0100
+++ b/rdf-concepts/index.html	Thu Aug 09 15:20:09 2012 +0100
@@ -730,7 +730,9 @@
     to this abstraction MAY be used in RDF, even if not defined
     in terms of XML Schema. RDF re-uses the XML Schema built-in datatypes,
     and provides two additional built-in datatypes,
-    <code><a>rdf:HTML</a></code> and <code><a>rdf:XMLLiteral</a></code>.</p>
+    <code><a>rdf:HTML</a></code> and <code><a>rdf:XMLLiteral</a></code>.
+    The list of datatypes supported by an implementation is determined
+    by its <a>datatype map</a>.</p>
 
     <p>A <dfn>datatype</dfn> consists of a <a>lexical space</a>,
     a <a>value space</a> and a <a>lexical-to-value mapping</a>, and
@@ -1079,12 +1081,20 @@
     then it MUST be paired with the datatype
     <code><a>rdf:XMLLiteral</a></code>.</p>
 
+    <p>If a <a>datatype map</a> contains the IRI
+    <code>http://www.w3.org/1999/02/22-rdf-syntax-ns#HTML</code>,
+    then it MUST be paired with the datatype
+    <code><a>rdf:HTML</a></code>.</p>
+
     <p>If a <a>datatype map</a> contains an IRI of the form
     <code>http://www.w3.org/2001/XMLSchema#<em>xxx</em></code>,
     then it MUST be paired with the
     <a title="RDF-compatible XSD types">RDF-compatible XSD type</a>
     named <code>xsd:<em>xxx</em></code>.<p>
 
+    <p>Specifications that <a href="#conformance">conform to RDF</a>
+    MAY impose additional constraints on the <a>datatype map</a>,
+    for example, require support for certain datatypes.</p>
 </section>
 
 
@@ -1211,12 +1221,25 @@
   <h2>Changes from RDF 2004</h2>
 
 
+<section class="appendix" id="changes-wd3">
+  <h3>Changes from 05 June 2012 WD to this version</h3>
+
+  <p>This section lists changes from the
+  <a href="http://www.w3.org/TR/2012/WD-rdf11-concepts-20120605/">05 June 2012 Working Draft (WD)</a> to this Editor's Draft of 
+  <em>RDF 1.1 Concepts and Abstract Syntax</em>.</p>
+
+  <ul>
+    <li>2012-08-09: Clarify that all datatypes are optional, but RDF-conformant specifications MAY require specific <a title="datatype map">datatype maps</a></li>
+  </ul>
+</section>
+
+
 <section class="appendix" id="changes-wd2">
-  <h3>Changes from FPWD to this version</h3>
+  <h3>Changes from FPWD to 05 June 2012 WD</h3>
 
   <p>This section lists changes from the
   <a href="http://www.w3.org/TR/2011/WD-rdf11-concepts-20110830/">First Public Working Draft (FPWD)</a>
-  to this Working Draft of 
+  to the <a href="http://www.w3.org/TR/2012/WD-rdf11-concepts-20120605/">05 June 2012 Working Draft (WD)</a> of
   <em>RDF 1.1 Concepts and Abstract Syntax</em>.</p>
 
   <ul>