Add <dc:variable name="variable" expr="xpath"/> construct to datacage language. Each time during traversal of the template this element is found a variable called 'variable' is set to the result of the the evaluation of the XPpath 'xpath'. Example: <dc:variable name="x" expr="$x + 1"/> <!-- Assign x+1 to x -->

CLASS
    NAME "POLYGON_BARRIERS"
    STYLE
        SIZE 5
        OUTLINECOLOR "#FF8000"
    END
END