Mark Gruenwald's rules for time travel in the Marvel comics were published in Marvel Age magazine in 1992 and are recounted here...Oh, yeah, the comics do that too. I think it started when they decided they wanted to revisit the dystopian future of "Days of Future Past," so they revealed that, instead of being erased as the original story implied, it had survived as an alternate possible future. Which was done for narrative reasons, but inadvertently came closer to making physical/logical sense.

The Jim Shooter Files: The Rules Of Time Travel for Marvel Comics
Last month's MCM London Comic Con had Jim Shooter as a guest, and at his table were a number of folders, binders, full of memos, sketches, artwork from
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