diff --git a/bin/nsupdate/nsupdate.docbook b/bin/nsupdate/nsupdate.docbook
index 42d113b34f..46c6187f8a 100644
--- a/bin/nsupdate/nsupdate.docbook
+++ b/bin/nsupdate/nsupdate.docbook
@@ -16,7 +16,7 @@
  - WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 -->
 
-<!-- $Id: nsupdate.docbook,v 1.9 2001/11/27 18:55:20 gson Exp $ -->
+<!-- $Id: nsupdate.docbook,v 1.10 2002/01/29 23:30:12 bwelling Exp $ -->
 
 <refentry>
 <refentryinfo>
@@ -81,10 +81,10 @@ made and the replies received from the name server.
 <para>
 Transaction signatures can be used to authenticate the Dynamic DNS
 updates.
-These use the TSIG resource record type described in RFC2845.
-The signatures rely on a shared secret that should only be known to
-<command>nsupdate</command>
-and the name server.
+These use the TSIG resource record type described in RFC2845 or the
+SIG(0) record described in RFC3535 and RFC2931.
+TSIG relies on a shared secret that should only be known to
+<command>nsupdate</command> and the name server.
 Currently, the only supported encryption algorithm for TSIG is
 HMAC-MD5, which is defined in RFC 2104.
 Once other algorithms are defined for TSIG, applications will need to
@@ -99,6 +99,8 @@ statements would be added to
 so that the name server can associate the appropriate secret key
 and algorithm with the IP address of the
 client application that will be using TSIG authentication.
+SIG(0) uses public key cryptography.  To use a SIG(0) key, the public
+key must be stored in a KEY record in a zone served by the name server.
 <command>nsupdate</command>
 does not read
 <filename>/etc/named.conf</filename>.
@@ -109,8 +111,8 @@ uses the
 <option>-y</option>
 or
 <option>-k</option>
-option to provide the shared secret needed to generate a TSIG record
-for authenticating Dynamic DNS update requests.
+option (with an HMAC-MD5 key) to provide the shared secret needed to generate
+a TSIG record for authenticating Dynamic DNS update requests.
 These options are mutually exclusive.
 With the
 <option>-k</option>
@@ -144,6 +146,11 @@ This may be visible in the output from
 or in a history file maintained by the user's shell.
 </para>
 <para>
+The <option>-k</option> may also be used to specify a SIG(0) key used
+to authenticate Dynamic DNS update requests.  In this case, the key
+specified is not an HMAC-MD5 key.
+</para>
+<para>
 By default
 <command>nsupdate</command>
 uses UDP to send update requests to the name server.
@@ -537,6 +544,9 @@ base-64 encoding of HMAC-MD5 key created by
 <refentrytitle>RFC2535</refentrytitle>
 </citerefentry>,
 <citerefentry>
+<refentrytitle>RFC2931</refentrytitle>
+</citerefentry>,
+<citerefentry>
 <refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>
 </citerefentry>,
 <citerefentry>