Originally Posted by
Menisk
If you want an absolute definition you'll have to contact the rules committee. As far as I'm concerned it just means that you're still able to lock the two wheels on the circuit that hasn't lost brake pressure, and hence can achieve the maximum braking ability able to be afforded to you by that end of the car. What they're trying to achieve is to make sure you have some ability to brake the car should you have a mechanical failure that takes a brake circuit out with it.