Update terms.

Author: gkellogg

common/terms.html

@@ -113,8 +113,9 @@
     consists of a string and a non-empty language tag
     as defined by [[BCP47]].
     The <dfn data-cite="RDF11-CONCEPTS#dfn-language-tag">language tag</dfn> MUST be well-formed
-    according to <a data-cite="BCP47#section-2.2.9">section 2.2.9 Classes of Conformance</a> of [[BCP47]],
-    and is normalized to lowercase.</dd>
+    according to <a data-cite="BCP47#section-2.2.9">section 2.2.9 Classes of Conformance</a> of [[BCP47]].
+    <span class="changed note">Processors MAY normalize <a>language tags</a> to lowercase.</span>
+  </dd>
   <dt><dfn data-cite="LINKED-DATA" data-no-xref="" class="preserve">Linked Data</dfn></dt><dd>
     A set of documents, each containing a representation of a <a>linked data graph</a> or <a>dataset</a>.</dd>
   <dt><dfn data-cite="RDF11-CONCEPTS#dfn-rdf-graph" data-lt="linked data graph|graph" class="preserve">RDF graph</dfn></dt><dd>