Horizontal Blinds, Roman Shades and RV Blinds. the correct cord to repair your blind. Polyester cord - resists effects of sunlight better than most other cords. All Cords are braided to minimize stretch and reduce friction.
I think the white stuff I got was 1.4mm but it looks ever so slightly smaller than my orange Ludwig cord, although it's pretty tough to "eyeball" tenths of a millimeter. Regardless, it works just fine.