NEW YORK (AP) — Payment processor Visa Inc. says it plans to start separately categorizing sales at gun shops. The move disclosed Saturday marks a major win for gun control advocates. They say it will help better track suspicious surges of gun sales that could be a preclude to a mass shooting. But gun rights advocates have argued such a step would unfairly segregate legal gun sales when most sales do not lead to mass shootings. Visa said it would adopt the International Organization for Standardization’s new merchant code for gun sales, just announced Friday. Until Friday, gun store sales were considered “general merchandise.” It joins Mastercard and AmEx, who said they would also start adopting the standard.