Designating a V score

Is there any proper convention for this? We have a board that we want a v score down the center so that the user can break it in two if needed.

I create another gerber file that contains the vscore lines, similar to the board outline gerber. I have not had any problems with Gold Phoenix doing it this way.

Diyparts:
Is there any proper convention for this? We have a board that we want a v score down the center so that the user can break it in two if needed.

If you are working with Gold Phoenix, just mark everything you want V-scored with silkscreen. When you send the files to Shane, just let him know that you indicated where you want the V-scores with silk. He is usually pretty good at conveying these little requests to the board house.