I have never seen or heard of this package type. Its a cross between a digipak (without the fixed plastic tray) and 2CD jewel case tray that swings (but only one CD holder). The plastic tray swings out of the way so you can read the liner. Has anyone seen this before?
There are several variations on Digipaks, it could just be one of them. But I’m having a hard time imagining how that tray is attached to the package, and how it swings to allow access the the panel behind. Do you think you could take a picture of the whole thing, standing open, something like this:
The cardboard is fitted into a slot in the plastic and a hole/plug is punched in the frame-to-cardboard to keep it in place. It all folds up nice and neat.
I’d call it an “other” as it is so unique.
It is kind of a Jewel Case tray, in a Gatefold card, but not glued like a Digipak.
Definitely keep those overview shots with the artwork.
Does it have any patent numbers on it or anything? Usually these really obscure packaging is under some kind patent system that never took off to mainstream 
Wouldn’t this be just another digipack variation (but not the brand Digipak®)?
It’s a multipanel cardboard sleeve with a plastic tray, which is what a digipack essentially is.
I’m torn, but leaning toward “Other.” Every digipak I’ve seen has the tray fully glued down. I think this is different enough from a typical digipak to call it something else. Like sound.and.vision, I’d be curious of any markings moulded into the plastic.
What about FLPpak?: Optical disc packaging - Wikipedia
Seems not very common, but I could find a photo on discogs: https://www.discogs.com/release/10317966
It looks a lot like the examples (but only frontal image present, no 3-dimensional view)
(I consider FLPpak stands for “flippack”? or something…)
Very close to the FLPpak, its called a"GCD PACK", found several references to them. I am not sure what the differences are, the wiki refers to a "latching closure into the right edge of the tray " which the GCD PACK does not have, otherwise they appear to be very close.
https://www.discogs.com/release/342739-Various-What-Is-Eternal
Its almost impossible to see the trademark name which is part of the plastic pressing of the tray on the back side.
Thank you everyone for helping solve this mystery.
I look at this and see something that is aimed at small production lines. The fact you can attach any carboard gatefold to the plastic tray and pin it to the plastic in a simple way makes me see a clever low production run system.
Very not a digipak.
