These packets are part of the 1.00 Mbit/s overhead in video applications. These packets contain navigation information for searching and seamless playback of the Video Object Unit (VOBU). The most important field in this packet is the sector address.

This shows where the first reference frame of the video object begins.

Advanced angle change and presentation timing are included to assist seamless playback. They are removed before entering the MPEG systems buffer, also known as the System Target Decoder (STD).