What are Flexbodies?

So I'm trying to figure out the Jbeam files and I've ran into a snag with the flexbodies.

So far I understand that flexbodies are what BeamNG uses to attach jBeam shapes to meshes in the game.

I'm confused by the section that follows this:

Code:

["mesh", "[group]:", "nonFlexMaterials"],

For example, we can look at the super.jbeam file and find this:

Code:

["super_chassis", ["super_chassis","super_shocktop_R","super_shocktop_F","super_uppermounts_F","super_lowermounts_a_F","super_lowermounts_b_F","super_uppermounts_R","super_lowermounts_R"]],

super_chassis is a mesh in the DAE file, I get that.

What I don't get is why it's here twice. And even further, why are there meshes in the DAE file now listed in the "group" section?

Is the super_chassis mesh inside the super_chassis mesh? Is the first instance of "super_chassis" just an arbitrary name that could be anything?

Then it gets worse.

Code:

["super_engbaycrap", ["super_chassis","super_shocktop_R","super_uppermounts_R","super_lowermounts_R"]],

Why is the chassis mesh INSIDE the engine bay crap group/mesh?

This makes absolutely zero sense to me.

 

Hopefully this picture should clarify it.

Here's the Barrier JBeam.
Basically as you see under the flexbodies, the barrier mesh (underlined blue), belongs to the "barrier" group(Highlighted yellow), and all the nodes marked in the red area, are the nodes for the "barrier" group.

Makes sense?


(imported from here)

 

Alright! Now it makes perfect sense. Thanks so much guys for the quick and clear responses!