I just looked into this a bit more.
The MC18 R5/6k has a headlight that measures about 11.5cm x 7.5cm in frontal area.

ADR 46/00 Headlamps, section 8 states:
8. STANDARD HEADLAMP

A headlamp shall be deemed to be a standard headlamp if it
8.1. Satisfies the above-mentioned requirements for approval;
8.2. Has an effective diameter of not less than 160 mm;

The area of a 16cm diameter headlight is about 200cm²
The area of an MC18 headlight is about 85cm²

Measure up your light. I'm guessing it will have a frontal area very close to 200cm²

Perhaps the ADR specs have changed over the years, but you get the picture, right?
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