Automotive ground clearance - how measured?

Factual Questions
1

Suggested by another topic regarding what is needed to drive in snow…

Is there a standard method that automakers use to measure “ground clearance” of their vehicles? Is it lowest point at the center of the vehicle (to exclude suspension items needed to attach wheels ) ? Or is it an average, say that most of the car is xxx above the ground, except for that bit of transmission or transfer case or oil pan that sits below that average?

So, if auto manufacture says vehicle has 5.9 inches of clearance, I can safely drive over any object that is less than that height (in an otherwise empty vehicle). And I won’t end up wrecking or denting etc any expensive stuff.

2

it should be to the lowest point in the vehicle to be useful
"ground clearance:
The vertical distance between level ground and the lowest fixed item on a vehicle (usually one of the differentials). " from http://www.100megsfree4.com/dictionary/car-dicg.htm