diff --git a/xep.ent b/xep.ent
index 8cfeff5e..3999cc8f 100644
--- a/xep.ent
+++ b/xep.ent
@@ -351,6 +351,7 @@
 <!ENTITY rfc2068 "<span class='ref'><link url='http://tools.ietf.org/html/rfc2068'>RFC 2068</link></span> <note>RFC 2068: Hypertext Transport Protocol -- HTTP/1.1 &lt;<link url='http://tools.ietf.org/html/rfc2068'>http://tools.ietf.org/html/rfc2068</link>&gt;.</note>" >
 <!ENTITY rfc2104 "<span class='ref'><link url='http://tools.ietf.org/html/rfc2104'>RFC 2104</link></span> <note>RFC 2104: HMAC: Keyed-Hashing for Message Authentication &lt;<link url='http://tools.ietf.org/html/rfc2104'>http://tools.ietf.org/html/rfc2104</link>&gt;.</note>" >
 <!ENTITY rfc2109 "<span class='ref'><link url='http://tools.ietf.org/html/rfc2109'>RFC 2109</link></span> <note>RFC 2109: HTTP State Mangement Mechanism &lt;<link url='http://tools.ietf.org/html/rfc2109'>http://tools.ietf.org/html/rfc2109</link>&gt;.</note>" >
+<!ENTITY rfc2111 "<span class='ref'><link url='http://tools.ietf.org/html/rfc2111'>RFC 2111</link></span> <note>RFC 2111: Content-ID and Message-ID Uniform Resource Locators &lt;<link url='http://tools.ietf.org/html/rfc2111'>http://tools.ietf.org/html/rfc2111</link>&gt;.</note>" >
 <!ENTITY rfc2119 "<span class='ref'><link url='http://tools.ietf.org/html/rfc2119'>RFC 2119</link></span> <note>RFC 2119: Key words for use in RFCs to Indicate Requirement Levels &lt;<link url='http://tools.ietf.org/html/rfc2119'>http://tools.ietf.org/html/rfc2119</link>&gt;.</note>" >
 <!ENTITY rfc2142 "<span class='ref'><link url='http://tools.ietf.org/html/rfc2142'>RFC 2142</link></span> <note>RFC 2142: Mailbox Names for Common Services, Roles and Functions &lt;<link url='http://tools.ietf.org/html/rfc2142'>http://tools.ietf.org/html/rfc2142</link>&gt;.</note>" >
 <!ENTITY rfc2144 "<span class='ref'><link url='http://tools.ietf.org/html/rfc2144'>RFC 2144</link></span> <note>RFC 2144: The CAST-128 Encryption Algorithm &lt;<link url='http://tools.ietf.org/html/rfc2144'>http://tools.ietf.org/html/rfc2144</link>&gt;.</note>" >