Happy International Emoji Calendar Day (!), a holiday I just made up to celebrate the arrival of a date that we, perhaps without realizing it, find ourselves staring at all year.

July 17 is enshrined in not one, but two Apple emoji — the calendar and the notepad. For Apple users, at least, “July 17” and “calendar” are synonymous. Some have, apparently, been anticipating this day anxiously.

And yet, this begs a critical question: Why July 17, of all the days in the year? Why not Jan. 1? Or Dec.r 25? Or Sept. 16 — the most popular date for U.S. births?

Per long-established Internet rumor, this is all a bit of self-referential back-slapping on Apple’s part: July 17 is the date iCal premiered at the MacWorld conference in 2002 (… and the date iCal displayed before start-up for several years). Everybody’s in on it. You’ll notice that Twitter’s emoji calendar displays July 15, and Google’s displays the number 12. Why? July 15 is widely considered the birthday of Twitter (happy belated!), and 12 is … the emoji designer’s birthday? We have nothing on that one, really.

In either case, this whole phenomenon serves as a good reminder that emoji don’t come from some kind of consistent, codified canon, beamed directly from Japan or the Unicode Consortium — the rendering of the characters (a.k.a., what they actually look like) is left up to individual platforms and thus varies across them. That’s an important detail to consider not only when discussing trivialities like International Emoji Calendar Day, but also when considering questions such as why emoji aren’t more diverse, or what the new set of characters will look like. But enough on that — let’s celebrate!