What is side seam length?
1) Side Seam
Or length of side measured from the top to the bottom of the trousers, starting from the top of the side seam at the hollowest part of the waist, and including the waistband. This measure should be taken tightly, and it is the leg itself, not the trousers, which is to be measured.
What is a side seam envelope?
Diagonal seam envelopes are pre die-cut and then folded and glued in a separate process. Side seam envelopes can be made that way as well and typically are when the order quantity is below 100,000 or so. Side seam construction is more typical and common on large runs because they are made on web-style equipment.