I just got an HP 46 (#1338S01941, no display option).
Someone has made an additional big rectangular opening
and two screw holes in the back panel by extending the
ventilation slots on the right side.
I've put two pictures at http://jan.our-isp.org/hp46/img1.jpg and http://jan.our-isp.org/hp46/img2.jpg
I'd like to know what the reason for this might have been.
My guess is, that the calculator was connected to some
laboratory equipment in order to collect data from experiments. Is this possible with an HP 46?