That reminds me of the time in High School when they
had all
of us in the 12th grade fill out this scanned form asking
all sorts of information I didn't think they needed. The form
was the type filled out with a #2 pencil and optically scanned.
I filled mine out (more or less correct, leaving answers I
didn't want to give blank), then took the extra time messing
with the control marks along the edge.
I don't know if the changed control marks had anything to do
with it, but we never got the results back.
Too bad you didn't go to my high school, 1980-1982...
We had two such scanners- a little one that you fed a master
into that had "the answers" and then subsequently the student
answer forms, and it checked and marked them directly.
Then we had a monster that was also programmable, but wrote
out a 9-track tape that we'd load onto the Kennedy on the Prime...
but IIRC, we could not get it to deal with the multiple marks.
So I had to write a PL/I program that would always mark
wrong any question with multiple answers.
;)