The Group ID of the first Group published in a track at application startup MUST be a unique integer that will not repeat in the future. One approach to achieve this is to set the initial Group ID to the creation time of the first Object in the group, represented as the number of milliseconds since the Unix epoch, rounded to the nearest millisecond. This ensures that republishing the same track in the future, such as after a loss of connectivity or an encoder restart, will not result in smaller or duplicate Group IDs for the same track name. Note that this method does not prevent duplication if more than 1000 groups are published per second.
Each subsequent Group ID MUST increase by 1.
If a publisher is able to maintain state across a republish, it MUST signal the gap in Group IDs using the MOQT Prior Group ID Gap Extension header.