during 1995 - 1996 the Beatles Anthology miniseries aired on TV (on Ay-Beatle-Cee in America of course) and 3 double disc sets containing outtakes, new engineered tracks, rare stuff and old gold from the days they called themselves the Quarrymen and more. The Anthology book came out a few years later (and it's a whopper - mamma mia, look at the size of the thing!).
During this time the American media referred to this as a "Beatles reunion" but since John Lennon was slain in 1980 there were only George Harrison, Ringo Starr and Paul McCartney around to promote the Anthology project. They posed for photos, gave a few impromptu performances and talked with the media. They themselves stated that this "reunion" was simply George, Ringo and Paul. In one now - famous photo the 3 are standing in front of a yellow tarp and Sir Paul is wearing round-lensed shades to honor John. Many sites in the Internet used the nickname "Threetles" to denote the three surviving Beatles.
1. The disbanded Beatles have worked together in various groupings and even all together, making some music that's still in "the can" but may see the light of day in the future. They have made guest appearances on each other's solo records as well, and they've worked on the Anthology together (in secret).
In early 1981 after John was killed by a nutcase in New York City Paul (with his wife Linda) and Ringo guested on a new hit by George. It was "All Those Years Ago", a tribute to John. It was on George's album, he wrote it, he sang it, he played guitar on it so it became a George hit. Technically it was a "Threetles" collaberation but no one officially called it that. The DJ on 92X said it was the 3 surviving Beatles.
2. The Threetles wrote, played and recorded at least 5 instrumental songs for the Anthology but they put them in the can as well since the 3 figured that those songs weren't really needed for the program. If they are ever released then under what name(s) will they be released as? It's just George, Ringo and Paul - the Threetles, not the Fab Four Beatles.
3. Since that time, sad to say, there can never be a "Threetles reunion" and a "Beatles reunion" is totally impossible - has been for quite some time. In late 2001, which was an ugly and horrible time to begin with, George Harrison died from lung cancer. Now there are only 2 Beatles left. R.I.P. George.