mapnik/tests/data/good_maps/markers_symbolizer_lines.xml

<!DOCTYPE Map>
<Map background-color="white" srs="+init=epsg:4326" minimum-version="0.7.2">
    <Style name="1">
        <Rule>
            <LineSymbolizer stroke-width=".2" stroke="grey"/>
            <MarkersSymbolizer
                file="shape://arrow"
                transform="scale(.8,.5)"
                stroke="green"
                stroke-width="1.3"
                fill="yellow"
                placement="line"
            />
        </Rule>
    </Style>

    <Layer name="point" srs="+init=epsg:4326">
        <StyleName>1</StyleName>
        <Datasource>
            <Parameter name="type">sqlite</Parameter>
            <Parameter name="file">../sqlite/qgis_spatiallite.sqlite</Parameter>
            <Parameter name="table">lines</Parameter>
        </Datasource>
    </Layer>

</Map>