Four bones counted as one? I'm somewhat of a beginner and I'm helping out a group of my friends by creating unity assets for them in blender. Recently I came across this avatar (made by Kevin Iglesias) and I've noticed its hand looks like it's made up of 4 bones, but is still considered by unity as a single bone (image below).

I can't find any mention of it anywhere; is it even possible to create something like this in Blender? Is it two different armatures that are parented with eachother?
I wrote to the author and he had explained it, I'll post the anwser here in case anyone else encounters this problem:

That's the representation in Unity of having 4 bone childs not connected.
In the picture below you will see that effect is achieved by having 4 not-connected-to-parent bone childs of the hand bone.