The approval mark in this Appendix affixed to an engine approved as a separate technical unit shows that the type concerned has been approved in Belgium (e 6), pursuant to this Regulation. The first two digits of the approval number (00) indicate that this engine approved as a separate technical unit was approved according to this Regulation. The following four digits (0004) are those allocated by the type-approval authority to engine approved as a separate technical unit as the base approval number.