I think what you're looking for is interLEAVE, not interleaf.
Interleaving is a means of "staggering" or "spacing" bits in a data stream. This spacing, staggering, spreading, allows for data recovery should you get a burst of noise such as ingress. It's used in 256k QAM systems, probably because of the amount of data modulated onto the carrier.
In the grand scheme of things, it's relatively unimportant until you take measurements like BER v/s MER. BER is a closer measurement than simple MER.
Does this help? Remember, I don't give refunds.
