diff --git a/xep.ent b/xep.ent
index 4c7a730f..7dc7f5aa 100644
--- a/xep.ent
+++ b/xep.ent
@@ -519,6 +519,7 @@ THE SOFTWARE.
 <!ENTITY rfc4627 "<span class='ref'><link url='http://tools.ietf.org/html/rfc4627'>RFC 4627</link></span> <note>RFC 4627: The application/json Media Type for JavaScript Object Notation (JSON) &lt;<link url='http://tools.ietf.org/html/rfc4627'>http://tools.ietf.org/html/rfc4627</link>&gt;.</note>" >
 <!ENTITY rfc4646 "<span class='ref'><link url='http://tools.ietf.org/html/rfc4646'>RFC 4646</link></span> <note>RFC 4646: Tags for Identifying Languages &lt;<link url='http://tools.ietf.org/html/rfc4646'>http://tools.ietf.org/html/rfc4646</link>&gt;.</note>" >
 <!ENTITY rfc4648 "<span class='ref'><link url='http://tools.ietf.org/html/rfc4648'>RFC 4648</link></span> <note>RFC 4648: The Base16, Base32, and Base64 Data Encodings &lt;<link url='http://tools.ietf.org/html/rfc4648'>http://tools.ietf.org/html/rfc4648</link>&gt;.</note>" >
+<!ENTITY rfc4685 "<span class='ref'><link url='http://tools.ietf.org/html/rfc4685'>RFC 4685</link></span> <note>RFC 4685: Atom Threading Extensions &lt;<link url='http://tools.ietf.org/html/rfc4685'>http://tools.ietf.org/html/rfc4685</link>&gt;.</note>" >
 <!ENTITY rfc4732 "<span class='ref'><link url='http://tools.ietf.org/html/rfc4732'>RFC 4732</link></span> <note>RFC 4732: Internet Denial-of-Service Considerations &lt;<link url='http://tools.ietf.org/html/rfc4732'>http://tools.ietf.org/html/rfc4732</link>&gt;.</note>" >
 <!ENTITY rfc4733 "<span class='ref'><link url='http://tools.ietf.org/html/rfc4733'>RFC 4733</link></span> <note>RFC 4733: RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals &lt;<link url='http://tools.ietf.org/html/rfc4733'>http://tools.ietf.org/html/rfc4733</link>&gt;.</note>" >
 <!ENTITY rfc4752 "<span class='ref'><link url='http://tools.ietf.org/html/rfc4752'>RFC 4752</link></span> <note>RFC 4752: The Kerberos V5 (&quot;GSSAPI&quot;) Simple Authentication and Security Layer (SASL) Mechanism  &lt;<link url='http://tools.ietf.org/html/rfc4752'>http://tools.ietf.org/html/rfc4752</link>&gt;.</note>" >