mapnik/tests/visual_tests/styles/marker-on-line-and-line-placement.xml

<Map>
<Style name="line" filter-mode="first" >
  <Rule>
    <LineSymbolizer stroke="red"/>
    <LineSymbolizer stroke="blue" smooth=".5"/>
    <LineSymbolizer stroke="orange" smooth="1"/>
    <LineSymbolizer stroke="green" smooth="1" geometry-transform="translate(10,10)" />
  </Rule>
</Style>
<Style name="point-placement" filter-mode="first" >
  <Rule>
    <MarkersSymbolizer stroke-width="0" allow-overlap="true" placement="line" marker-type="ellipse" fill="red" />
    <MarkersSymbolizer stroke-width="0" offset="-10" transform="translate(0,-10)" allow-overlap="true" placement="line" marker-type="ellipse" fill="darkred" />
    <MarkersSymbolizer stroke-width="0" allow-overlap="true" smooth=".5" transform="translate(10,10) translate(-10,-10)" placement="line" marker-type="ellipse" fill="blue" />
    <MarkersSymbolizer stroke-width="0" allow-overlap="true" smooth="1" placement="line" marker-type="ellipse" fill="orange" />
    <MarkersSymbolizer stroke-width="0" allow-overlap="true" smooth="1" geometry-transform="translate(10,10)" placement="line" marker-type="ellipse" fill="darkgreen" />
  </Rule>
</Style>
<Layer name="carto_tests">
    <StyleName>line</StyleName>
    <StyleName>point-placement</StyleName>
    <Datasource>
       <Parameter name="type">csv</Parameter>
       <Parameter name="file">../data/marker-on-line.csv</Parameter>
       <Parameter name="separator">|</Parameter>
    </Datasource>
  </Layer>
</Map>