mapnik/tests/visual_tests/styles/lines-multi-layout-shield.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE Map>
<!-- Upright test -->
<Map background-color="white" srs="+proj=latlong +datum=WGS84">

    <Layer name="layer" srs="+proj=latlong +datum=WGS84">
        <StyleName>lines</StyleName>
        <StyleName>text</StyleName>
        <Datasource>
            <Parameter name="type">csv</Parameter>
            <Parameter name="file">../data/lines.csv</Parameter>
        </Datasource>
    </Layer>

    <Style name="lines">
        <Rule>
            <LineSymbolizer stroke-width="3" stroke="red"/>
        </Rule>
    </Style>

    <Style name="text">
        <Rule>
            <ShieldSymbolizer placement="line" spacing="60" minimum-distance="10" label-position-tolerance="0.5" face-name="DejaVu Sans Bold" size="14" fill="#ffffff" file="../../data/svg/rect.svg">
                [nr]
                <Format size="10" face-name="DejaVu Sans Book" fill="#000000" halo-fill="rgba(255,255,255,0.6)" halo-radius="1.5">
                    <Layout dy="-10">"SOUTH"</Layout>
                    <Layout dy="10">"ALT"</Layout>
                </Format>
            </ShieldSymbolizer>
        </Rule>
    </Style>

</Map>