The 407 Express Toll Route (or 407 ETR for short) is an tolled highway in Ontario that currently stretches from the QEW/403 interchange in Burlington easterly around Toronto to Highway 7 just east of Brougham. There are no toll booths, instead, usage is tracked either through the use of a transponder, or barring that, through video capture of your license plate.
For the longest time, you may have seen a sign similar to this on the 407 ETR.
By way of background, the intent of this sign was to say that if your vehicle was not equiped with a 407 ETR transponder, you'd be charged a Video Toll charge of $3.60. However, one possible interpretation of the above sign is that there would be no fee charged at all if you didn't have the transponder. Surely this ambiguity meant that some people potentially could have disputed the video toll charge, if they were so inclined.
These signs were amended sometime in September of 2008. By adding a question mark decal after the 'No Transponder' text, there is no more ambiguity.
Goes to show, one bit of punctuation could make all the difference!