    package flare.vis.data.render
    {
        /**
         * Utility class defining arrow types for directed edges.
         */
        public class ArrowType
        {
            /** Indicates that no arrows should be drawn. */
            public static const NONE:String = "none";
            /** Indicates that a closed triangular arrow head should be drawn. */
            public static const TRIANGLE:String = "triangle";
            /** Indicates that two lines should be used to draw the arrow head. */
            public static const LINES:String = "lines";

            /**
             * This constructor will throw an error, as this is an abstract class.
             */
            public function ArrowType()
            {
                throw new Error("This is an abstract class.");
            }

        } // end of class ArrowType
    }