Fang Zei said:
IIRC, Zombie mentioned somewhere (either on savestarwars or secrethistoryofstarwars) that the negatives were assembled in an A-B fashion. That is, over/under/over/under and so forth. This allowed the SE team to remove and replace the relevant pieces of negative without destroying any frames.
well that certainly is a relief, I hope that's true. I haven't heard that before but I've always been skeptical of Lucas being willing to permanently sacrifice frames.