What size Flat head Machine screws are used to attach a Compur #00 retaining ring to the lensboard?

What size flat head machine screws are used to attach a Compur #00 retaining ring to the lensboard? There are three cone shaped holes in the back of the retaining ring for the Compur #00 shutter attached to my 90mm B&J lens. Are these holes used to attach the retaining ring to the lensboard, or just for the tool that tightens the shutter to the ring, to slip into, as one of the holes, has three scratches in the paint leading from it, in a clockwise direction? It's an aluminum Shen Hao made Linhof lensboard, if that makes any difference. The ring fits really tight in the hole, but the shutter still rotates, and I'm wondering if the screws make any difference. It didn't have any screws attaching it to the lensboard I found it in.