Mapserver ANCHORPOINTS with SVG symbols, SVG output - What's going on?

map.svg

square.svg

svg.map

MAP
  NAME SVG_ICON_ANCHORPOINT_TEST
  STATUS ON
  SIZE 100 100
  EXTENT 0 0 0.001 0.001
  IMAGECOLOR 255 255 255

  IMAGETYPE svg

  CONFIG "MS_ERRORFILE" "stderr"

  SYMBOL
    NAME "square_0_0"
    TYPE svg
    IMAGE "./square.svg"
    ANCHORPOINT 0 0
  END
  SYMBOL
    NAME "square_05_05"
    TYPE svg
    IMAGE "./square.svg"
    ANCHORPOINT 0.5 0.5
  END
  SYMBOL
    NAME "square_1_1"
    TYPE svg
    IMAGE "./square.svg"
    ANCHORPOINT 1 1
  END
  SYMBOL
    NAME "DEBUG"
    TYPE ellipse
    FILLED true
    POINTS
      1 1
    END
  END

  LAYER
    TYPE POINT
    STATUS ON
    FEATURE
      POINTS
        0.0004 0.0005
      END
      TEXT "P"
    END
    CLASS
       STYLE
         SYMBOL "square_0_0"
       END
       STYLE
         COLOR 255 0 0
         SYMBOL "DEBUG"
       END
    END
  END
  LAYER
    TYPE POINT
    STATUS ON
    FEATURE
      POINTS
        0.0005 0.0005
      END
      TEXT "P"
    END
    CLASS
       STYLE
         SYMBOL "square_05_05"
       END
       STYLE
         COLOR 255 0 0
         SYMBOL "DEBUG"
       END
    END
  END
  LAYER
    TYPE POINT
    STATUS ON
    FEATURE
      POINTS
        0.0006 0.0005
      END
      TEXT "P"
    END
    CLASS
       STYLE
         SYMBOL "square_1_1"
       END
       STYLE
         COLOR 255 0 0
         SYMBOL "DEBUG"
       END
    END
  END

END

Thanks for all of this research. Added to docs as a note (MapServer/MapServer-documentation#446)