is not.
    </para>

    <para>
     An important implementation difference between polygons and
     paths is that the stored representation of a polygon includes its
     smallest bounding box.  This speeds up certain search operations,
     although computing the bounding box adds overhead while constructing
     new polygons.
    </para>

    <para>
     Values of type <type>polygon</type> are specified using any of the
     following syntaxes:

<synopsis>
( ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> ) )
  ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ... , ( <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )
  ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable>   , ... ,   <replaceable>xn</replaceable> , <replaceable>yn</replaceable> )
    <replaceable>x1</replaceable> , <replaceable>y1</replaceable>   , ... ,   <replaceable>xn</replaceable> , <replaceable>yn</replaceable>
</synopsis>

     where the points are the end points of the line segments
     comprising the boundary of the polygon.
    </para>

    <para>
     Polygons are output using the first syntax.
    </para>
   </sect2>

   <sect2 id="datatype-circle">
    <title>Circles</title>

    <indexterm>
     <primary>circle</primary>
    </indexterm>

    <para>
     Circles are represented by a center point and radius.
     Values of type <type>circle</type> are specified using any of the
     following syntaxes:

<synopsis>
&lt; ( <replaceable>x</replaceable> , <replaceable>y</replaceable> ) , <replaceable>r</replaceable> &gt;
( ( <replaceable>x</replaceable> , <replaceable>y</replaceable> ) , <replaceable>r</replaceable> )
  ( <replaceable>x</replaceable> , <replaceable>y</replaceable> ) , <replaceable>r</replaceable>
    <replaceable>x</replaceable> , <replaceable>y</replaceable>   , <replaceable>r</replaceable>
</synopsis>

     where
     <literal>(<replaceable>x</replaceable>,<replaceable>y</replaceable>)</literal>
     is the center point and <replaceable>r</replaceable> is the radius of the
     circle.
    </para>

    <para>
     Circles are output using the first syntax.
    </para>
   </sect2>

  </sect1>

  <sect1 id="datatype-net-types">
   <title>Network Address Types</title>

   <indexterm zone="datatype-net-types">
    <primary>network</primary>
    <secondary>data types</secondary>
   </indexterm>

   <para>
    <productname>PostgreSQL</productname> offers data types to store IPv4, IPv6, and MAC
    addresses, as shown in <xref linkend="datatype-net-types-table"/>.  It
    is better to use these types instead of plain text types to store
    network addresses, because
    these types offer input error checking and specialized
    operators and functions (see <xref linkend="functions-net"/>).
   </para>

    <table tocentry="1" id="datatype-net-types-table">
     <title>Network Address Types</title>
     <tgroup cols="3">
      <colspec colname="col1" colwidth="1*"/>
      <colspec colname="col2" colwidth="1*"/>
      <colspec colname="col3" colwidth="2*"/>
      <thead>
       <row>
        <entry>Name</entry>
        <entry>Storage Size</entry>
        <entry>Description</entry>
       </row>
      </thead>
      <tbody>

       <row>
        <entry><type>cidr</type></entry>
        <entry>7 or 19 bytes</entry>
        <entry>IPv4 and IPv6 networks</entry>
       </row>

       <row>
        <entry><type>inet</type></entry>
        <entry>7 or 19 bytes</entry>
        <entry>IPv4 and IPv6 hosts and networks</entry>
       </row>

       <row>
        <entry><type>macaddr</type></entry>
        <entry>6 bytes</entry>
        <entry>MAC addresses</entry>
       </row>

       <row>
        <entry><type>macaddr8</type></entry>
        <entry>8 bytes</entry>
        <entry>MAC addresses (EUI-64 format)</entry>
       </row>

      </tbody>
     </tgroup>
    </table>

   <para>
    When sorting <type>inet</type>