Article: You want to baste a certain portion of the seam line. You baste this portion as basting stitches can be undone easily. The basting line will be removed once the fly zipper is installed.  You will start sewing at the bottom of the pant fronts and sew upward towards the outward flaps. At a certain point, you will stop sewing and begin basting. Consult your pattern to see how many inches you sew upward before you begin basting. Find the point where you begin basting with a ruler and mark it with a pen. You can mark the beginning of the baste line with a dot, a horizontal line, or another marking of your choosing.

What is a summary?
Mark where the sewing line ends and the basting line begins.