public boolean equals(Object obj) {
        if (obj == this) {
            return true;      
        }
        if (obj instanceof XYItemEntity && super.equals(obj)) {
            XYItemEntity ie = (XYItemEntity) obj;
            if (this.series != ie.series) {
                return false;   
            }
            if (this.item != ie.item) {
                return false;   
            }
            return true;
        }
        return false;