Sew order refers to the sewing order that needs to be followed to best put the block together. In these machine piecing directions, the B and D triangles must be sewn together first. Then these units are sewn into rows with other pieces. Finally the rows are sewn together to complete the quilt block.
CAUTION: The sew order of a pattern can vary depending on the method used to put it together. Sometimes the order of sewing pieces by hand will be different than machine sewing.