Ski Construction of "Butter Zones"

I was just wondering how exactly these flex points are created. I'd imagine they just decrease the amount of material. But I'm wondering how the construction differs more specifically.

Do the Tanner Hall, Fujative, and STLs all achieve this trough the same technique, or do the companies do it differently.

An example of what im interested in is something like the Line explanation for the Invaders.

"Francois came up with a special core profile that is actually milled thinner in front and behind of the binding to create a hinge point."

Thanks