It doesn't require permission.
"SRAM offers the use of the standard and XD trademark to companies that conform to the technical specification and agree to abide by the terms of our license agreement."
It does require that you don't attempt to change it or patent some modification of it, among other things. Plenty to balk at if you're Shimano.
May 31, 2019, 2:52 p.m. - Alex D
It doesn't require permission. "SRAM offers the use of the standard and XD trademark to companies that conform to the technical specification and agree to abide by the terms of our license agreement." It does require that you don't attempt to change it or patent some modification of it, among other things. Plenty to balk at if you're Shimano.