diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
new file mode 100644
index a39cb8f..04e3e54
*** a/doc/src/sgml/ref/alter_table.sgml
--- b/doc/src/sgml/ref/alter_table.sgml
*************** ALTER TABLE [ IF EXISTS ] <replaceable c
*** 387,393 ****
     </varlistentry>
  
     <varlistentry>
!     <term><literal>CLUSTER</literal></term>
      <listitem>
       <para>
        This form selects the default index for future
--- 387,393 ----
     </varlistentry>
  
     <varlistentry>
!     <term><literal>CLUSTER ON</literal></term>
      <listitem>
       <para>
        This form selects the default index for future