I know what it's for!
stevce has a blue MO, and the blue dot tells them what colour to paint the car.
Every one else's car was "supposed" to be blue, but there was demand for other colours, so they over-rode the blue.
Maybe not. Maybe the valve and balancing part makes more sense.
I can ask my mechanic who always seems to know about all of these things.
Drunk driver, eh? ... I once lost my truck and 2 years of work (well, two years of paid sick leave is not the worst thing that has ever happened to me), but ... zero tolerance is fine with me!