 I became a mechanic, and this is where it comes in. A zero number on a number line, zero on a number line is a balanced air-fuel mixture. All right? A positive number means we're adding fuel because the mixture is lean. A negative number means we're taking fuel away because the mixture is rich. And we're doing this plus and minus, this add and subtraction, by changing pulse width on the injector, how long the injector is open for. Okay? Okay.