In Scotland, pleating to the stripe is traditional for a military kilt, compared to pleating to the sett for a civilian kilt.
I wanted a kilt in Royal Air Force tartan for my volunteer duties at an aviation museum but was not eligible as although my father had served in the RAF, I had only ever served as an Air Training Corps cadet and never joined the full time service.
After some persuasion the Royal Air Force agreed to supply their tartan on condition that the kilt was produced by their official kiltmaker and would be pleated to the sett, as the RAF Dress Code kilt for Dining In events is always pleated to the stripe.