Linear Online edit systems have varying degrees of sophistication in assembly. Most conventional controllers have two assembly modes: A-mode and B-mode.
An A-mode assembly takes the first edit in the list, then the next, and so on. This is a sequential lookup.
B-mode (sometimes called checkerboard), in contrast, applies a search which records the first edit, then finds the next edit with the same reel name, and so on. When edits from the first reel are exhausted, the search finds the first edit with a new reel name, then finds the next edit with that reel name, and so on. Thus B-mode performs the edits in groups of reel names by picking them out of the list one by one.
While B-mode assemblies are an important tool in the online room, an Edl intentionally sorted into a particular sequence must be assembled in A-mode to preserve the sequence. This is especially important when Preread has been applied. For this reason, EdlMax processing assumes the list will be assembled in A-mode (sequential) sequence by the online controller.