RSG lets you set individual halftone options (screen ruling, screen angle and dot shape) for objects and images which override those provided by the current MPD. You can do this when Color Separations in the Printer Setup dialog box is unchecked - that is, when you're not making color separations, or when Color Separations in the Printer Setup dialog box is checked and the required objects or images are to be spot color separated (this is specified using the Color Specifications and Separation Options dialog boxes)

To set individual halftone options for objects created in RSG - rules, rectangles, ovals, polygons and picture borders - use the Pen Screen and Fill Screen dialog boxes (via the Pen Screen and Fill screen buttons in their Specification sheets).

To set individual halftone options for grey-level images in picture blocks, use the Halftone Screen dialog box (via the Halftone button in the Image Control dialog box).
Options in these dialog boxes are as described in the Printing section later, with the addition of the Elliptical halftone dot shape.