B171 was exhibited at Kunstausstellung Kühl, where the installation photograph (fig. 1) was taken, and later at Mannheim and Frakfurt.

The photograph also shows B154.

Fig. 3 shows the installation with perspective corrected.

B154 (fig. 4) is used to try and make sense of the shades of grey.

B171 has been 'squared' as its dimensions are known to be 50x50cm.

The upper right corner is thought to be blue. The dark smudge bottom left, only noticed at this stage could be black and the middle section at the bottom yellow.