Updated regexp for language tags.
--- a/rdf-concepts/index.html	Fri May 10 00:11:56 2013 -0500
+++ b/rdf-concepts/index.html	Fri May 10 10:50:29 2013 -0400
@@ -636,7 +636,8 @@
 
 		<p class="note" id="note-language-tag-regex">
 		Implementors might wish to note that language tags conform to the
-		regular expression <code>'@' [a-zA-Z]+ ('-' [a-zA-Z0-9]+)*</code>
+		regular expression <code>’@’ [a-zA-Z]{1,8} (’-’
+		[a-zA-Z0-9]{1,8})*</code>
 		before normalizing to lowercase.</p>
 
     <p>Concrete syntaxes MAY support <dfn title="simple literal">simple