Dear Arno, dear Bill,
thx a lot for your fast response, help and explanations.
Seems that I had the wrong memories, despite I am only 50 years old ;-))
Now I have a better picture for the purpose of the 2 grooves. My Amel is not equipped to use them.
I will hoist the genoa in the single slot and everything is fine again.
Amel 54 119 Lady Charlyette, last day in Le Marin