In the English language, x is often used to refer to an unknown variable, a practice that got its start in mathematics. It later made the jump over to pop culture in the 80s and 90s to refer to something that is just... unknown. See Mega Man games happening in 200X, for example. [...] The usage here is that it's some unknown time in the future. It's a deliberate vagueness of when the events take place.
—ShortFatOtaku, An X For Latinx
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