RSG gives you several ways to format text, all of which give you the same choices for fonts, sizes, leading, typestyles, indents, color, etc.
A stylesheet is used to define a set of type specs for one element in your design - body text, a head, a footer or display type. You use each stylesheet to format a selection of text quickly and consistently.

The stylesheet does not prevent you from formatting the text in other ways, using the Format menu or Edit menu commands or the Type Specs dialog box, provided that the stylesheet does not contain the same type spec. If there is a conflict, the stylesheet overrides other formatting controls.
For example, if the stylesheet is determining the font, then you cannot change it using Format menu commands unless you either remove the stylesheet from formatting the selected text, or change the stylesheet so that the option for Font is None.
For details about each type spec, see Specifying Type Specs, later in this chapter.