diff --git a/doc/src/sgml/advanced.sgml b/doc/src/sgml/advanced.sgml
index 218988e..75b1bd4 100644
--- a/doc/src/sgml/advanced.sgml
+++ b/doc/src/sgml/advanced.sgml
@@ -237,6 +237,16 @@ COMMIT;
     <command>COMMIT</>, and all our updates so far will be canceled.
    </para>

+   <note>
+     <para>
+      A few things in the database are exempt from rollback.  The most
+      important are <literal>SEQUENCE</>s - which are used by the counters in
+      <literal>SERIAL</> columns. See <xref linkend="functions-sequence">.  Any
+      function or type with special transactional behavior will have an explanatory
+      note in its documentation.
+     </para>
+   </note>
+
    <para>
     <productname>PostgreSQL</> actually treats every SQL statement as being
     executed within a transaction.  If you do not issue a <command>BEGIN</>
@@ -251,8 +261,8 @@ COMMIT;
     <para>
      Some client libraries issue <command>BEGIN</> and <command>COMMIT</>
      commands automatically, so that you might get the effect of transaction
-     blocks without asking.  Check the documentation for the interface
-     you are using.
+     blocks without asking. Client libraries often call this "autocommit".
+     Check the documentation for the interface you are using.
     </para>
    </note>

diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index afc82a2..cbde801 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -800,7 +800,19 @@ NUMERIC
      <type>bigserial</type> are not true types, but merely
      a notational convenience for creating unique identifier columns
      (similar to the <literal>AUTO_INCREMENT</literal> property
-     supported by some other databases). In the current
+     supported by some other databases).
+    </para>
+
+    <important>
+      <para>
+        Because they use <literal>SEQUENCE</literal>s, serial data types are
+	exempt from transactional rollback. This means they can have "holes"
+        or gaps where values are discarded. See <literal>nexval()</literal> in
+	<xref linkend="functions-sequence"> for details.
+      </para>
+    </important>
+
+    <para>In the current
      implementation, specifying:

 <programlisting>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 157de09..0296d3a 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -9820,6 +9820,27 @@ nextval('foo'::text)      <lineannotation><literal>foo</literal> is looked up at
         execute <function>nextval</function> concurrently, each will safely receive
         a distinct sequence value.
        </para>
+
+       <important>
+        <para>
+         To avoid blocking concurrent transactions that obtain numbers from the
+         same sequence, a <function>nextval</function> operation is never rolled back;
+         that is, once a value has been fetched it is considered used, even if the
+         transaction that did the <function>nextval</function> later aborts.  This means
+         that aborted transactions might leave unused <quote>holes</quote> in the
+         sequence of assigned values.  <function>setval</function> operations are never
+         rolled back, either.
+        </para>
+       </important>
+
+       <para>
+        If a sequence object has been created with default parameters,
+        successive <function>nextval</function> calls will return successive values
+        beginning with 1.  Other behaviors can be obtained by using
+        special parameters in the <xref linkend="sql-createsequence"> command;
+        see its command reference page for more information.
+       </para>
+
       </listitem>
      </varlistentry>

@@ -9883,31 +9904,17 @@ SELECT setval('foo', 42, false);    <lineannotation>Next <function>nextval</> wi
         The result returned by <function>setval</function> is just the value of its
         second argument.
        </para>
+       <important>
+        <para>
+         Changes to sequences made by setval() are not undone if the transaction
+         rolls back. See the note on nextval().
+        </para>
+       </important>
       </listitem>
      </varlistentry>
     </variablelist>
   </para>

-  <para>
-   If a sequence object has been created with default parameters,
-   successive <function>nextval</function> calls will return successive values
-   beginning with 1.  Other behaviors can be obtained by using
-   special parameters in the <xref linkend="sql-createsequence"> command;
-   see its command reference page for more information.
-  </para>
-
-  <important>
-   <para>
-    To avoid blocking concurrent transactions that obtain numbers from the
-    same sequence, a <function>nextval</function> operation is never rolled back;
-    that is, once a value has been fetched it is considered used, even if the
-    transaction that did the <function>nextval</function> later aborts.  This means
-    that aborted transactions might leave unused <quote>holes</quote> in the
-    sequence of assigned values.  <function>setval</function> operations are never
-    rolled back, either.
-   </para>
-  </important>
-
  </sect1>