Abstract: A clean-room wall including vertically extending wall profile members (2,4,6) against which one or several wall panels (10) are mounted. In their sides, facing the interior (14) of the room, the profiles are formed substantially parallel with the wall extending flanges (8) against which the wall panel is arranged from the outside, as seen from the interior of the room. Fastening mechanisms (12) are arranged at the outside of the wall panel for fastening of the panel to the profile flange members.

Abstract: An error preventing incremental measuring system utilizes a plurality of scanning elements associated to a relatively movable divided scale. But, instead of merely comparing the results of a plurality of independent channels originating at the scanning elements and terminating at separate counters, the system according to the invention combines the signals from the scanning elements by way of a logical network into a further signal similar resp. dissimilar to one or more of the scanning signals, thus avoiding the necessity of fault tolerances.