When the dot shape is set to Square or Line, the Dot Properties area is configured as follows:
Phantasm Halftone Dot Properties - Square/Line
All of the parameters used for the Circle dot shape (with the exception of Roundness and Detail, which are not applicable) apply to Square and Line. The Line shape option constructs each “dot” out of a single, straight, stroked path. The line’s end caps are always set to rounded; if a different style end cap is required, there are two methods. The first is to add the additional Astute Graphics live effect Stroke Attributes, which can modify the end caps. The second method is to simply use a Square shape type instead, and change the Scale W parameter to be smaller than the Scale H.