diff --git a/doc/src/sgml/indices.sgml b/doc/src/sgml/indices.sgml
new file mode 100644
index 95c0a19..c54bf0d
*** a/doc/src/sgml/indices.sgml
--- b/doc/src/sgml/indices.sgml
*************** CREATE INDEX test1_lower_col1_idx ON tes
*** 706,711 ****
--- 706,720 ----
    </para>
  
    <para>
+    Expression indexes also allow control over the scope of unique indexes.
+    For example, this unique index prevents duplicate integer values from
+    being stored in a <type>double precision</type>-typed column:
+ <programlisting>
+ CREATE UNIQUE INDEX test1_uniq_int ON tests ((floor(double_col)))
+ </programlisting>
+   </para>
+ 
+   <para>
     If we were to declare this index <literal>UNIQUE</literal>, it would prevent
     creation of rows whose <literal>col1</literal> values differ only in case,
     as well as rows whose <literal>col1</literal> values are actually identical.
*************** CREATE UNIQUE INDEX tests_success_constr
*** 946,951 ****
--- 955,970 ----
      This is a particularly efficient approach when there are few
      successful tests and many unsuccessful ones.
     </para>
+ 
+    <para>
+     This index allows only one null in the indexed column by using a
+     partial index clause to process only null column values, and using
+     an expression index clause to index <literal>true</literal> instead
+     of <literal>null</literal>:
+ <programlisting>
+ CREATE UNIQUE INDEX tests_target_one_null ON tests ((target IS NULL)) WHERE target IS NULL;
+ </programlisting>
+    </para>
    </example>
  
    <para>