Allowed @id: null and term: null in grammar section.
--- a/spec/latest/json-ld-syntax/index.html Fri Dec 21 21:29:57 2012 +0100
+++ b/spec/latest/json-ld-syntax/index.html Sat Dec 22 12:53:38 2012 -0500
@@ -2966,24 +2966,23 @@
its value MUST have the lexical form of <tref>absolute IRI</tref> or be <tref>null</tref>.</p>
<p><tref>Term</tref> values MUST be either a
- <tref>string</tref>, or an <tref>expanded term definition</tref>.</p>
+ <tref>string</tref>, <code>null</code>, or an <tref>expanded term definition</tref>.</p>
<p>An <tdef>expanded term definition</tdef> is used to describe the mapping
between a <tref>term</tref> and its expanded identifier, as well as other
properties of the value associated with the <tref>term</tref> when it is
used as key in a <tref>node object</tref>.</p>
-<p>An <tref>expanded term definition</tref> MUST be a <tref>JSON object</tref>
+<p>An <tref>expanded term definition</tref> SHOULD be a <tref>JSON object</tref>
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. [@@@ the previous statements contradict themselves]
- All values associated with <code>@id</code> MUST expand to an <tref>absolute IRI</tref>.</p>
-<p>If the <tref>term</tref> definition is not a <tref>compact IRI</tref> or <tref>absolute IRI</tref>,
+ <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>expanded term definition</tref> contains the <code>@id</code> <tref>keyword</tref>,
- its value MUST be 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>
+ 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>
<p>If the <tref>expanded term definition</tref> contains the <code>@type</code> <tref>keyword</tref>,
its value MUST be an <tref>absolute 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 the <code>@id</code> <tref>keyword</tref>.</p>
<p>If the <tref>expanded term definition</tref> contains the <code>@language</code> <tref>keyword</tref>,