I like to call these discoveries as unknown unknowns. It’s when not only the answer/fact is not known, but even the existence of the question/fact is unknown.

I like to call these discoveries as unknown unknowns. It’s when not only the answer/fact is not known, but even the existence of the question/fact is unknown. In this case, not only the fact that the format is ambiguous (the answer), but also the fact that there exists something interesting/unusual about the format (the question). For example, you could have learned the answer if you could have searched “is there something unusual about the format?”, or even “is the format actually ambiguous?”, but those ideas were not present! Active mentors can help with this a lot.