- * @return List { Object { .. } } Boolean: true/false for major/minor mark,
- * Integer: marker position in alignment column coords, String: null
- * or a String to be rendered at the position.
+ * @param av
+ * @param startx
+ * left-most column in visible view
+ * @param endx
+ * - right-most column in visible view
+ * @return List of ScaleMark holding boolean: true/false for major/minor mark,
+ * marker position in alignment column coords, a String to be rendered
+ * at the position (or null)