I noticed the same error made by journalist who started using the GenX term interchangeably with twentysomething in the 1980s and continuing to do so for more than a decade.  I guess the best argument is that the term X is a variable in algebra to stand for any value so the variable label X is constantly being re-used to stand for different things, and that X doesn't stand for any fixed thing.  However, this argument loses steam once we realize the whole term is Gen X and not just X.    

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