What a good question! I am no expert, so no doubt an answer will be forthcoming from those that know, but as far as I know, they are just called large setts of a particular tartan.

If I may, can I add a question or three? With these large setts how difficult is it to pleat say a knife pleated kilt to the sett? Is it easier to pleat to the stripe? Alright, I understand some tartans are quite complicated, but for example how about a Montgomery, or a MacNeil?