bright-line

[Ruifeng]

"I think we are at one of those bright-line moments in history when things could change in ways that we can hardly imagine and across a very broad number of areas simultaneously."

What does bright-line mean?

Thanks

[Mister Micawber]

It does not seem to hold any of the limited definitions that the phrase has online. I suggest that the writer has generalized from its very specific spectrographic and legal meanings and has used it to mean 'critical'.
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Native English teacher at Mister Micawber's