C wasn't designed originally as an international programming language. Its choice of characters was based on the more or less standard U.S. keyboard. The international popularity of C, however, has led to several extensions supporting different and larger character sets. This section of the reference provides an overview of these additions.
Some keyboards don't provide all the symbols used in C. Therefore, C provides alternative representations of several symbols with a set of three-character sequences, called trigraph sequences. Table RS.VII.1 lists these trigraphs.