Harry Benjamin's Sex Orientation Scale (S.O.S.) was an attempt to classify and understand various forms and subtypes of transvestism and transsexualism in biological males. It was a seven-point scale (with three types of transvestism, three types of transsexualism, and one category for typical males); it was analogous to the Kinsey scale of sexual orientation, which also had seven categories. Much like Kinsey's understanding of sexual orientation, Dr. Benjamin understood the nature of gender identity and gender expression not as a discrete scale, but as a spectrum, a continuum with many variations, much more than those featured in the scale. But the scale he developed seemed to be an easy, rational and clinically useful way to diagnose different forms of transsexualism and to distinguish b