No. Those are not marks on the sail, they are reinforcements. Notice the narrow band of brighter white color on the luff also? Same thing. Each sailmaker designs their sails in a way that they believe offers superior performance characterisitics to the competitors' sails. You could probably Google Illbruck to learn who did their sails and then read what they were trying to do. I think that was a Volvo race boat and they have to have spinnakers that can stand up to thousands of miles of high speed, heavy wind use (not your everyday sail).