2.1. Model A of the certificate of conformity (complete vehicle) shall cover vehicles which can be used on the road without requiring any further stage for their approval.2.2. Model B of the certificate of conformity (completed vehicles) shall cover vehicles which have undergone a further stage for their approval.This is the normal result of the multi-stage approval process (e.g. a bus built by a second stage manufacturer on a chassis built by a vehicle manufacturer).The additional features added during the multi-stage process shall be described briefly