The mark consists of a miscellaneous design made up of three groups of circles and six biconcave lines, namely, one group of three large circles and two long biconcave lines, one group of three medium circles and two medium biconcave lines, and one group of small circles and two short biconcave lines arranged as follows: the group of large circles appears on the left-hand side of the mark and in that group one circle is shown in the North position, one circle is shown in the West position, and one circle is shown in the South position, the circle in the North position is connected to the circle in the West position by a long biconcave line, and the circle in the West position is connected to the circle in the South position by a long biconcave line; the group of medium circles appears on the right-hand side of the mark and in that group one circle is shown in the North position, one circle is shown in the East position, and one circle is shown in the South position, the circle in the North position is connected to the circle in the East position by a medium biconcave line, and the circle in the East position is connected to the circle in the South position by a medium biconcave line; and the group of small circles appears in the middle of the mark in the same arrangement as the group of large circles but with small circles and short biconcave lines.