5.6. Where a device has been found to comply with the requirements of several Regulations, a single approval mark may be applied comprising a circle according to paragraph 5.5.1., the approval numbers and the additional symbols appropriate to each Regulation under which approval has been granted. The size of the components of this single approval mark shall not be less than the minimum size required for the smallest of the individual marks under a Regulation, under which approval has been granted. a0c0