Fenix UI question

Hey, I've been thinking about switching the led in my old l1d which got me thinking. How does the UI work for fenix flashlights where you can change modes by twisting the head? I don't get how the loosening of the head changes modes.

With the head loose it grounds through the threads, when it's tight the body makes contact and grounds to the board itself.

When you open the head to swap the emitter you may (or not) see a third wire connected to the head itself instead of the emitter board, this will be the ground for the "head loose" set of modes.

EDIT: My description is for lights with clicky switch for on/off and head twist for dual mode sets.

Hmm, looks like I'll need to do more reading. Still new to lights and electronics in general. Any links about how the grounding works?

I want to try and build a light and have 2 modes but switched by twisting the head (like a tk11), has anyone done this?

EDIT:
So from reading, I should ground the + end of the led to the outer copper ring on a board. There for when tightened, it will be HIGH mode only.

Then I should make the threads/pill connected normally (so it does not bypass the microprocessor).

So when tightened and there is contact with the copper edge on the driver, it will bypass the microprocessors but not any regulation. Then when loosened, the current will go through the threads and go through the microprocessor (which I somehow set to a lower output).