Pleats: These lines are matched up to create pleats on the cut out fabric pieces. Darts: These lines are for matching up to create darts within the fabric pieces. Arrows: Grainline arrows are used to show which direction to pin the pattern on the fabric. The grainline runs parallel to the fabric edge. Notches: Shown as triangles or small lines, these are marked on the edges and are mainly used for matching up pattern pieces.