Gets or sets an array of 2 or 3 PointF structures specifying a callout line attached to the free text annotation. 3 points represent the starting coordinates, the knee point, and the ending coordinates of the line. 2 points represent the starting and ending coordinates of the line. The coordinates are specified in PDF user space. The positive X axis extends horizontally to the right, and the positive Y axis extends vertically upward, with the origin usually in the lower left corner of the page.