REBEL 3D

How is the flow control during printing in Marlin?
I assume that:
- Flow 0 = flow of the first layer
- Flow = flow of all other layers
So the possibility of percentage change of flow, which will be generated by slicr.
If this is really the case, then I have one more question later.
Thanks

Is Marlin's "Flow" setting a universal percentage multiplier for all extrusion, or does it only affect layers *after* the first? In my experience, adjusting "Flow" seems to impact all layers, including the initial one, even with first layer flow compensation.Does anyone else have similar experience with the "Flow" setting influencing the first layer?

Is flow really adjusted per layer like that? I always thought it was a global setting. When I tried adjusting it on my Ender 3, the initial layer seemed unaffected by changes to overall flow.