mapnik/tests/data/good_maps/datasource.xml

<!-- see: http://trac.mapnik.org/changeset/574 -->
<Map bgcolor="steelblue" srs="+proj=longlat +ellps=airy +datum=OSGB36 +no_defs">

    <Style name="test">
      <Rule>
         <PolygonSymbolizer />
      </Rule>
    </Style>

    <Datasource name="shp">
    <Parameter name="type">shape</Parameter>
    <Parameter name="base">../../data/shp/</Parameter>
    </Datasource>

  <Layer name="lay" srs="+proj=longlat +ellps=airy +datum=OSGB36 +no_defs">
    <StyleName>test</StyleName>
    <Datasource base="shp">
      <Parameter name="file">poly.shp</Parameter>
    </Datasource>
  </Layer>
  
</Map>