A common misconception is that the disc spins first in one direction, and then another, either for PTP or OTP recording, when in fact DVD-Writers always spin a disc in the clockwise direction. A simpler way to understand what's written above is to think of the little hole in the centre of the DVD as the "inside" and the rim of the DVD as the "outside". Since dual-layer DVDs have two data layers, placed one on top of the other – Layer 0 (L0) and Layer 1 (L1), there are two ways in which these two layers may be written to - L0, inside to outside and then L1 inside to outside again (PTP), or L0 inside to outside and then L1 outside to inside (OTP). OTP is usually used for DVD-Video, to prevent the inherent delay that PTP involves: in PTP, the laser head moves from the outside edge of the DVD to the inside to start reading L1 when it reaches the end of L0. This results in the video skipping or freezing up for some time as the laser head repositions itself and the system waits to start receiving data again.