gistfile1.xml

<Layer name="<data_layer>"
  srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
    <StyleName>style1</StyleName>
    <StyleName>style2</StyleName>
    <StyleName>style3</StyleName>
    <StyleName>style4</StyleName>
    <Datasource>
       <Parameter name="type"><![CDATA[postgis]]></Parameter>
       <Parameter name="table"><![CDATA[thetablename]]></Parameter>
       <Parameter name="key_field"><![CDATA[]]></Parameter>
       <Parameter name="geometry_field"><![CDATA[]]></Parameter>
       <Parameter name="extent_cache"><![CDATA[auto]]></Parameter>
       <Parameter name="extent"><![CDATA[theextent]]></Parameter>
       <Parameter name="dbname"><![CDATA[thedbname]]></Parameter>
       <Parameter name="host"><![CDATA[theremotehost]]></Parameter>
       <Parameter name="user"><![CDATA[theuser]]></Parameter>
       <Parameter name="password"><![CDATA[thepassword]]></Parameter>
       <Parameter name="simplify_geometries"><![CDATA[true]]></Parameter>
    </Datasource>
  </Layer>