If my memory serves me correctly, previous to 2000-01, when "intentionally" was added to the rule, officials had to observe and note if the ring vibrated (or not) due to a slap or strike on the backboard while the ball is in flight during try or tap.
Back then, before the rule change, if the ring vibrated, be it by an intentional, deliberate, incidental, or accidental slap, or strike, a technical foul was charged.
Of course, back in ancient times, most backboards were bolted to the walls of the gymnasium, and didn't hang from the ceiling, or from free standing stanchions.
It would take a major earthquake to vibrate most backboards back then.
Am I right Mark T. DeNucci, Sr?