It is confusing, but you are right. Short frame implies height, but Glock already handled that by naming the models with abbreviated grip height (combined with shorter barrel-frame top-ends) with a different model number. I believe Glock felt that by calling it "Slim Frame" there would be an implication that the grip is narrower in width (LEFT to RIGHT) and this would be reinforced by all the advertising that Walther and Kahr are doing these days about their pocket 9s and 380s. So, what term to describe shorter front-to-back dimension on the grip frame? Short Frame... Not perfect, but there it is...