As for patents; " A patent provides protection
for up to twenty years,
counting from the filing date (the date given with reference numeral 22 on
the front page). US patents with a filing date before June 8, 1995 provide
protection for up to seventeen years counting from the date of grant (the
date given with reference numeral 45), or 20 years from the filing date,
whichever expires later. "
Correct, but trackballs date to the 1950s.
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Will