The ruler markings depend on the enlargement factor set for the drawing area. When you change the enlargement, the ruler markings are changed accordingly. The greater the enlargement selected, the more detailed the marking lines and the dimension values appear.

The dimensions on the vertical ruler are shown under the longer marking lines. On the horizontal ruler, they are shown to the right of the marking lines. The dimensions underneath/to the left of the zero point have a - in front of the value.

The unit of measurement (mm, inch, point) in which the dimensions are shown depends on the setting on the Drawing preferences panel. You can change the unit of measurement at any time. When the rulers are visible, the dimensions are shown directly in the unit that has just been set.