Infinity symbol in bookbinding to indicate that a book is printed on acid-free paper and will therefore be long-lasting. In modern mysticism, the infinity symbol has become identified with a variation of the ouroboros, an ancient image of a snake eating its own tail that has also come to symbolize the infinite, and the ouroboros is sometimes drawn in figure-eight form to reflect this identification, rather than in its more traditional circular form. In the works of Vladimir Nabokov, including "The Gift" and "Pale Fire", the figure-eight shape is used symbolically to refer to the Möbius strip and the infinite, for instance
Degree symbol degree such as minute (′), second (″), and third (‴), which originate as small raised Roman numerals. In the case of degrees of angular arc, the degree symbol follows the number without any intervening space (e.g., 30°). The addition of minute and second of arc units follow the degree units, with intervening spaces between the units but no spaces between the numbers and arc symbols (e.g., 30° 12′ 5″). In the case of degrees of temperature, three scientific and engineering standards bodies (BIPM, ISO and the U.S. Government Printing Office) prescribe printing temperatures with a space between the number and