hinges
I have a set of these hinges (at least, they seem to be hinges) but I'm not sure what they're for.
They measure about 1.5" (3cm) in the longest direction.
Here are some odd features:
No obvious way to attach the parts on the left with the one on the right!
Setscrew in U-shaped piece (second photo)
I assume these would be surface-mounted, they seem too thick to mortise into anything.
Plan A) I'd try to remove the glue, fill the holes†, let it set and then re-drill the holes
Plan B) Use repair plates designed for this job Example
Plan C) If all fails I'd spend $10 on one of these, put it in my old electric drill's chuck and relocate the hinges.
† Using maybe something like an "Interior Wood Filler that holds screws and nails".
To directly answer the question: The panel release allows the hinge to be separated into two parts, so the door can be dismounted without removing the screws and later snapped back into position. (Essentially, it gives you the same capability that removing the hinge pin would in a more traditional design.)
Best Answer
Hinge?
I look at that and see a clamp to assemble two panels at right-angles which is designed for easy assembly or disassembly and flat-packing.