My guess is box-pleating for sewn pleating.
If you look on Matts site he has several examples of surviving box-pleated
kilts. I think one reason for box-pleats is that it takes less clothe.
Clothe then like nowdays was expensive. I believe that the military
used box-pleats for just that reason-costs.

My box-pleated kilt is heavy weight clothe and just about exactally
4 yards.

Anyho, I really like the looks of a box-pleat-you just don't see that many
examples anymore,knife-pleating being the rage. And I like older styles
myself.

dave