$FreeBSD$

--- modules/registrar/doc/registrar_user.sgml
+++ modules/registrar/doc/registrar_user.sgml
@@ -29,7 +29,12 @@
 		    </listitem>
 		    <listitem>
 			<para>
-			    <emphasis>sl - Stateless Replies</emphasis>.
+			    <emphasis>sl - Stateless Replies (if <varname>use_tm</varname> is 0)</emphasis>.
+			</para>
+		    </listitem>
+		    <listitem>
+			<para>
+			    <emphasis>tm - Transaction module (if <varname>use_tm</varname> is 1)</emphasis>.
 			</para>
 		    </listitem>
 	    	</itemizedlist>
@@ -321,6 +326,31 @@
 modparam("registrar", "retry_after", 30)
 ...
 		</programlisting>
+	    </example>
+	</section>
+
+	<section>
+	    <title><varname>use_tm</varname> (integer)</title>
+	    <para>
+		If set to 1 then the registrar will use <function>t_reply()</function> function from
+		the tm module instead of <function>sl_send_reply()</function> function from the sl
+		module for sending replies.  This allows registration transactions to be processed
+		statefully if necessary.  When set to 1 script writer need to ensure that transaction
+		exists when <function>save()</function> is called, usually by calling
+		<function>t_newtran()</function>.
+	    </para>
+	    <para>
+		<emphasis>
+		    Default value is 0.
+		</emphasis>
+	    </para>
+	    <example>
+		<title>Set <varname>use_tm</varname> parameter</title>
+		<programlisting format="linespecific">
+...
+modparam("registrar", "use_tm", 1)
+...
+</programlisting>
 	    </example>
 	</section>