My '75 doubleneck has markers for every fret, but I can't remember what kind - it's currently hanging out at the Mothership. I think it's dots for everything - normal dots where they would be on a fretted bass (3, 5, 7, 9, 12, etc.) and then different dots at each fret. Will post a pic soon when I retrieve it - dug through my archives and never took a photo of that aspect!