Just in case you DO have a screw loose, and don't have a driver that fits, check out Lara Speciality Tools. They carry an extensive series of funky screwdriver bits.
From the traditional slotted to the rare tri-groove nut setter these guys have it all.
They do call our good old Canadian Robertson a "square recess".
And
for more trivia, did you know that the screwdriver (created in Europe)
is the only major mechanical device not independently invented by the
Chinese? (from One Good Turn: A Natural History of the Screwdriver and the Screw, Witold Rybczynski, Harper Flamingo Canada, Toronto, 2000)
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