The dangerous bend or cautionsymbol ☡ ( U+2621 ☡ CAUTION SIGN ) It resembles aroad sign that indicates a "dangerous bend" in the road ahead, and is used to mark passages tricky on a first reading or with an especially .
Others have used variations of the symbol in their textbooks, and computer scientist Donald Knuth introduced an American-style road-sign depiction in his Metafont and TeX systems, with a pair of adjacent signs indicating doubly dangerous passages.