--- a/rdf-concepts/index.html	Wed Nov 09 20:06:37 2011 +0000
+++ b/rdf-concepts/index.html	Thu Nov 10 00:25:45 2011 +0000
@@ -853,6 +853,13 @@
     but were not well-formed according to [[!BCP47]]. Such
     language tags do not conform to RDF 1.1.</p>
 
+    <p class="note">The <code>xsd:string</code> datatype does not
+    permit the <code>#x0</code> character, and implementations may not permit
+    control codes in the <code>#x1-#x1F</code> range. Earlier versions of
+    RDF allowed these characters in
+    <a title="simple literal">simple literals</a>, although they
+    could never be serialized in a W3C-recommended concrete syntax.</p>
+
       <p class="note">When using the language tag, care must be
       taken not to confuse language with locale. The language
       tag relates only to human language text. Presentational
@@ -1166,6 +1173,7 @@
 
   <ul>
     <li>2011-11-09: Updated the two sections on literals to reflect the <a href="http://www.w3.org/2011/rdf-wg/track/issues/71">ISSUE-71</a> resolution that literals with language tag now have the datatype IRI <code>rdf:langString</code>. Formally introduced the term “language-tagged string”.</li>
+    <li>2011-11-09: Add a note that explains that #x0-#x1F are no longer allowed in simple literals
     <li>2011-08-13: Updated Turtle reference to Turtle FPWD</li>
     <li>2011-07-21: Condensed the 2004 acknowledgements</li>
     <li>2011-07-21: Updated the two sections on literals to reflect the <a href="http://www.w3.org/2011/rdf-wg/track/issues/12">ISSUE-12</a> resolution that simple literals are no longer part of the abstract syntax. Formally introduced the terms “language-tagged literal”, “simple literal”.</li>