Some 7-bit national character sets [[ISO/IEC 646]] setsdo redefinenot have curly brackets tobracket characters that make programs hardly readable on such designed terminals. To address this problem, BCPL hadhas digraphs '''$(*''' and '''*$)''' for <tt>'''{</tt>''' and <tt>'''}</tt> (same as Pascal),''' and [[ANSI C]] introduced ''[[C trigraph|trigraph]]s'' that can be used instead of such problematic characters. All trigraphs consist of two [[question mark]]s (“??”) followed by a character that is not redefined in the national 7 bit ASCII character sets. TheIn C, the trigraphs for ‘'''{’''' and ‘'''}’''', respectively, are “'''??<'''” and “'''??>'''”.
