## 9.1 Tick marks

class `tick_mark.T`
  Tick marks are used in conjunction with line plots ( see Section 9) to show where sample points are. Class `tick_mark.T` is an abstract base class, from which several built-in tick mark classes are derived. They are described later.

Class `tick_mark.T` supports the following set of attributes.

`fill_style`
  Type: fill_style.T ( see Section 16) Default: fill_style.white.

  The fill style.

`line_style`
  Type: line_style.T ( see Section 14) Default: line_style.black.

  The line style of the tick mark.

`size`
  Type: length in points ( See Section 4) Default: 5.

  Size of the tick mark.

Several types of tick marks are offered by PyChart as subclasses of `tick_mark.T`. They include: tick_mark.Circle, tick_mark.Square, tick_mark.Triangle, tick_mark.DownTriangle, tick_mark.X, tick_mark.Plus, tick_mark.Diamond, tick_mark.Star, tick_mark.Null. Specific instance of these classes are also defined for your convenience. Below is the list of such standard tick marks. They are referred to by as "`tick_mark.`name", where name is the labels below them.