I think he means how does he use it?
Well normally this is an option in the drive's firmware (chipset) and 99% of newer burning software supports it by default.
If it is ON then if the data transfer is to slow, the disc speed also slows down in order to write the data. If it is OFF then if the data transfer is to slow, the disc cannot keep up with it and you get a "burn error" and disc is partionally written.
You want it ON or burn at a very slow speed, like 4x.