Conferences and journals worldwide set deadlines "Anywhere on Earth", which means a date has not ended until it ends in UTC-12. Enter your deadline date. The Authority will pronounce.
UTC-12 contains almost nothing. Its only land is Baker Island and Howland Island, two uninhabited US atolls near the equator, administered as wildlife refuges. Every "23:59 AoE" on the planet is, formally, 23:59 here, on the local time of a place where no one has ever submitted anything.
Yes. Anywhere on Earth, UTC-12, is a genuine convention used by IEEE, major academic conferences, and standards bodies for deadlines. The islands are real, the timezone is real, and the emptiness is real. Only the Authority is invented, which it considers a technicality.
If the deadline is AoE, yes, as long as the date survives in UTC-12. The Authority provides this fact as a public service and accepts no responsibility for what reviewers can tell about work submitted at 11:58 AoE. They can tell.
Formally, the day expires over Baker and Howland Islands and the surrounding ocean. No official is present for the ceremony. The Authority likes to think a frigatebird glances at the horizon.
Yes, UTC+14, kept by Kiribati's Line Islands, which are inhabited and reach each date first. The Authority maintains a formal rivalry with them, conducted entirely by never communicating, as befits a 26-hour separation.