$CD, $COPDIST, $COUPLE_DISTANCE

Distance from each other at which vehicles stop before coupling. The value is inherited in the section hierarchy. This value is stored as an evaluated number in the section hierarchy - so, if you use a random expression, it will be evaluated at the point you define it, and exactly the same value will be inherited. The default value is 1/6th of the vehicle height as specified in the Stock List $IMGY parameter.