Brother 2340CV Operation Manual page 20

Actual examples of two needles three threads cover stitch sewing
1) Hems of T-shirts
(Simple stitch)
3) Attaching tape
(edges of collars, etc) (Binding)
5) Attaching elastic
(Hem with sewn-in elastic)
Actual examples of three-needles four-threads cover stitch sewing
1) Plain stitching
4) Circular hemming
18
2) Stitches
(Top stitched seams/Ribbing/Yokes)
6) Attaching lace
(Flat joining seam)
2) Hem stitching
5) Elastic lace attaching
4) Decorative stitching
(Decorative stitching)
7) Belt loop sewing
(Belt loop sewing)
3) Tape attaching