Updated Context processing algorithm to allow resetting @id: null.
--- a/spec/latest/json-ld-api/index.html Sat Dec 22 12:53:38 2012 -0500
+++ b/spec/latest/json-ld-api/index.html Sat Dec 22 13:48:23 2012 -0500
@@ -1023,15 +1023,29 @@
<li>If <tref>term definition</tref> for <em>key</em> exists in the
<tref>active context</tref>, remove it.</li>
<li>Initialize a new, empty <tref>term definition</tref> <em>definition</em>.</li>
- <li>If <em>value</em> has an <code>@id</code> member with a value <em>val</em>
+ <li>If <em>value</em> has an <code>@id</code> member with a value <em>val</em>:
<ol class="algorithm">
- <li>and <em>val</em> is an <tref>array</tref>, expand each item according the
- <a href="#iri-expansion">IRI Expansion algorithm</a>. If an item is not a <tref>string</tref>,
- raise an <code class="error">INVALID_PROPERTY_GENERATOR</code> error; otherwise sort
- <em>val</em> and store it as <tref>IRI mapping</tref> in <em>definition</em>.</li>
- <li>Otherwise, if <em>val</em> is a <tref>string</tref>, expand it according the
- <a href="#iri-expansion">IRI Expansion algorithm</a>. Set the <tref>IRI mapping</tref> of
- <em>definition</em> to the expanded <em>val</em>.</li>
+ <li>if <em>val</em> is <tref>null</tref>, set
+ <em>definition</em> to <em>val</em>.
+ <li>if <em>val</em> is an <tref>array</tref>, process each
+ <em>item</em> in the array:
+ <ol class="algorithm">
+ <li>if <em>item</em> is a <tref>string</tref> expand it
+ according the <a href="#iri-expansion">IRI Expansion algorithm</a>.
+ </li>
+ <li>otherwise, raise an
+ <code class="error">INVALID_PROPERTY_GENERATOR</code>
+ error.
+ </li>
+ </ol>
+ <li>if <em>val</em> is an <tref>array</tref>,
+ lexicographically sort <em>val</em> and set
+ <em>definition</em> to <em>val</em>.</li>
+ <li>Otherwise, if <em>val</em> is a <tref>string</tref>,
+ expand it according the
+ <a href="#iri-expansion">IRI Expansion algorithm</a> and
+ set <em>definition</em> to <em>val</em>.
+ </li>
</ol>
</li>
<li>If the <tref>IRI mapping</tref> of <em>definition</em> is set to <tref>null</tref> or a