This guide discusses the measurements and markings for the back neckline and shoulder area when draping or sewing a dress. It provides instructions on locating the center back neck point, measuring down from that point to find the appropriate length for the back neckline, and determining the shoulder slope based on the intersection of the neck and shoulder points.

Instructional steps:

1. Locate the center back neck point on the dress form or pattern.
2. From the center back neck point, measure down a certain distance (in this case, 4.5-5 inches or 12-13 cm) to find the appropriate length for the back neckline.
3. Identify the intersection of the neck and shoulder points on the side.
4. From the neck point on the side, draw a straight line down to determine the shoulder slope.
5. Note that the measurements provided may not be exact for different dress sizes or body shapes, and adjustments may be necessary.