diff --git a/docs/manual/programs/htdigest.xml b/docs/manual/programs/htdigest.xml
index fc9df711a6..1459a8d446 100644
--- a/docs/manual/programs/htdigest.xml
+++ b/docs/manual/programs/htdigest.xml
@@ -57,7 +57,10 @@
     exist, or deleted and recreated if it does exist.</dd>
 
     <dt><code><var>realm</var></code></dt>
-    <dd>The realm name to which the user name belongs.</dd>
+    <dd>The realm name to which the user name belongs. See 
+    <a href="http://tools.ietf.org/html/rfc2617#section-3.2.1">
+    http://tools.ietf.org/html/rfc2617#section-3.2.1</a> for more details.
+    </dd>
 
     <dt><code><var>username</var></code></dt>
     <dd>The user name to create or update in <var>passwdfile</var>. If