Выражение встречается в следующем контексте:

Assembly the two material on the sewing head and make the seam on the reverse side of the Flap - with a PLK unit (if avalaible) to have the final Flap dimension

or instead that You use a PLK unit You make it by manual way the seam (wrong seam or You need to mark it before to make the seam)

текстильная тематика
Заранее спасибо