Screening refers to applying less ink to an object when it is plotted. The object appears dimmer on the screen and output to paper. Screening can be used to help differentiate objects in a drawing without changing the objects' color properties.
To assign a screening value to an object, you must assign a plot style to the object, and then define the screening value in that plot style.
You can assign a screening value from 0 to 100. The default setting, 100, means no screening is applied, and the object is displayed with normal ink intensity. A screening value of 0 means the object contains no ink and is thus invisible in that viewport.