I posed this same question to Steve Goodrich a couple of months ago and unfortunately, he was also at loss for an explanation. You would think there would be some reason to the numbering. If they were numbered by "release" time, would that make the earlier chips more valuable/collectable? For example, an "Axxx" being older and more desirable than a "Qxxx". I've got an A003 in my collection and I'm eager to hear an explanation of this.