When I was attending junior high school in the early 1970s type was still divided into gothic (sans serif) and Roman (serif) classifications, and in the serif fonts the term Roman additionally indicated the "base" version of the font ("Roman" as opposed to "Light" or "Condensed"). This was the time when what are now classified as "humanist" sans-serif fonts such as "Optima" and "Serif Gothic" were becoming more established, and challenging the assumption that all "Gothic" fonts had uniform line weight and were without serifs. This is why that simplistic differentiation was replaced by the newer, more accurate classifications.