mapnik/tests/visual_tests/styles/formatting-expr-alignment.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE Map>
<Map background-color="white" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
  <FontSet name="book">
    <Font face-name="DejaVu Sans Book"/>
  </FontSet>

  <Layer name="layer" srs="+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs">
    <StyleName>My Style</StyleName>
    <Datasource>
      <Parameter name="type">csv</Parameter>
<Parameter name="inline">
lat,long,horizontal_alignment,vertical_alignment,dy,text
 0.25,-0.35,left,top,0
 0.25,-0.12,middle,top,0
 0.25, 0.11,right,top,0
 0   ,-0.35,left,middle,0
 0   ,-0.12,middle,middle,0
 0   , 0.11,right,middle,0
-0.25,-0.35,left,bottom,0
-0.25,-0.12,middle,bottom,0
-0.25, 0.11,right,bottom,0
# right column: auto vertical alignment
 0.25, 0.35,right,auto,-0.0001
 0   , 0.35,middle,auto,0
-0.25, 0.35,left,auto,0.0001
      </Parameter>
    </Datasource>
  </Layer>

    <Style name="My Style">
    <Rule>
      <PointSymbolizer ignore-placement="true"/>
      <TextSymbolizer fontset-name="book" size="16" placement="point" dx="0" dy="[dy]" vertical-alignment="[vertical_alignment]" horizontal-alignment="[horizontal_alignment]">XX</TextSymbolizer>
    </Rule>
  </Style>

</Map>