The mark consists of two vertical rectangles, slightly offset, wherein sits a circle. The lines of the rectangle set slightly lower and to the right are approximately twice the thickness of the lines of the other rectangle. The circle is set within the rectangles such that there is an equal amount of space on each side between the edge of the circle and the nearest vertical line. One fifth of the vertical space is above the circle, two fifths below the circle, such that the circle occupies two fifths of the space in the upper portion of the rectangles..