Single slashes indicate something intended as an expression or a sign-vehicle, while guillemets indicate something intended as content. Therefore /xxxx/ means, expresses or refers to «xxxx». When there is no question of phonology, verbal expressions will be written in their alphabetic form. However, since this book is concerned not only with verbal signs but also with objects, images or behavior intended as signs, these phenomena must be expressed through verbal expressions: in order to distinguish, for instance, the object automobile from the word automobile, the former is written between double slashes and in italic. Therefore //automobile// is the object corresponding to the verbal expression /automobile/, and both refer to the content unit «automobile». Single quotation marks serve to emphasize a certain word; double marks are used for quotations. Italic denotes terms used in a technical sense.