--- a/spec/latest/json-ld-syntax/index.html	Thu Dec 27 14:53:24 2012 +0100
+++ b/spec/latest/json-ld-syntax/index.html	Thu Dec 27 14:58:31 2012 +0100
@@ -3012,9 +3012,10 @@
   composed of zero or more keys from <code>@id</code>,
   <code>@type</code>, <code>@language</code> or <code>@container</code>. An
   <tref>expanded term definition</tref> SHOULD NOT contain any other keys.
-<p>If the <tref>term</tref> definition is not <code>null</code>, a <tref>compact IRI</tref>, or an <tref>absolute IRI</tref>,
-  the <tref>expanded term
-  definition</tref> MUST include the <code>@id</code> key.</p>
+<p>If the <tref>term</tref> definition is not <code>null</code>, a <tref>compact IRI</tref>,
+  or an <tref>absolute IRI</tref> and the <tref>active context</tref> does not have an
+  <code>@vocab</code> mapping, the <tref>expanded term definition</tref> MUST
+  include the <code>@id</code> key.</p>
 
 <p>If the <tref>expanded term definition</tref> contains the <code>@id</code> <tref>keyword</tref>,
   its value MUST be <code>null</code>, an <tref>IRI</tref>, a <tref>compact IRI</tref>, a <tref>term</tref> defined in the defining <tref>context definition</tref> or the <tref>active context</tref>, or an <tref>array</tref> composed of any of the previous allowed values.</p>