Several manufacturers are often involved in the construction of a motorhome. The vehicles are then homologated in stages. For example, the powerhead from FIAT with a COC (stage 1) can be assembled with a frame-rear axle attachment from e.g. Al-Ko (COC stage 2) to form a chassis. The body manufacturer Carado then builds a motorhome on top of this and issues a Carado COC (level 3) accordingly. Often there is only level 1 (e.g. Fiat) and level 2 (Carado), as the chassis manufacturer builds directly onto the ladder frame.
When it comes to topics such as the permissible tyres or load/unloadings, the COC of the last level is always decisive.