Solid: a solid rectangle surrounding the annotation. Dashed: a dashed rectangle surrounding the annotation. Dash is the line length in point, Gap is the distance in point between the dashed lines. line or arrow comment displays a single straight line on the page. You can change the look (color, opacity, border style and so on. For the arrow drawing, you can edit the beginning and ending straight lines so they use arrows and other pointer styles. When opened, it displays a pop-up window containing the text of the associated note to explain each drawing in more detail. : a dashed rectangle surrounding the annotation. Dash is the line length in point, Gap is the distance in point between the dashed lines. The constant opacity value to be used in painting the annotation. This value applies to all visible elements of the annotation in its closed state (including its background and border) but not to the popup window that appears when the annotation is opened. The opacity vary from 0.0 (no contribution) to 1.0 (maximum contribution). true, the text specified by the Contents should be replicated as a caption in the appearance of the line. The text should be rendered in a manner appropriate to the content, taking into account factors such as writing direction. A positive value means that the leader lines appear in the direction that is clockwise when traversing the line from its starting point to its ending point, a negative value indicates the opposite direction. Source.