[ma2rten]

Your use of the phrase makes no sense. It's the "no parking" that proofs the rule and not the exception.

[ddalex]

that's actually the correct use of the phrase "the exception proves the rule"

the rule is that the parking is allowed; the exception is that it's not allowed on Wednesdays; they didn't bother spelling out "parking is allowed at all other times except"

[parineum]

"No parking on Wednesday between 9-12pm"

Imagine you got a parking ticket on Tuesday. What would your defense in court be?