3 generation of languages were powered by increased level of abstraction, which was enabled by increased capabilities of hardware. 4th generation can (will?) be powered by AI.

Just because it's on Wikipedia doesn't mean it's a real thing. The only source for that page is some bizarro, circa-1998 website about "computer jargon". These are not academic terms that I've personally ever heard of. Happy to be wrong, but I'm not going to pretend they have any utility or legs.

3gl 4gl 5gl were common terms 30 years ago or so. More industry and advertising terms than academic. And 5gl was more like a Japanese government grant program than any particular set of language features IIRC.

My memory of the whole "nGL" language thing was that it was more a marketing term than anything you would find in an academic paper. It was particularly common in the IBM world, for example in books[1] and advertisements[2]

[1] https://www.oldcomputerbooks.com/pages/books/R504/james-mart...

[2] I can't find a good example, but I remember seeing ads for "4GL" tools in Dr Dobbs regularly in the mid-90s.

On PC, I remember platforms such as dBase were often referred to as 4GL. In retrospect, it feels like was a short way to say "very high-level domain-specific language for databases".