Maybe Hugo could confirm this. Warning: this is a Comet touring fender. The chain guard is on the clutch side
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The dents are clearance for the RFM. There is only one dent on this side because there is no need for a lower dent because the chain guard relief takes away the need. Thus, the dent in the center is for the upper part of the RFM. If this were a twin mudguard it would need another dent down towards the bottom front of the mudguard.
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The other side. The Comet has no chain on this side. It shows the two dents you need for the RFM. The hole below the dent is the lower mudguard mount bolt hole.
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You can see how the mudguard is waisted at the lower swing arm. The upper mounting hole was not drilled in this mudguard for some reason.
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This is the waist necessary for the upper part of the RFM.
Obviously, you have to fit your own RFM to get the proper clearance, but you can see by the photos that the dents are not small.
David