- 1.1 This International Standard contains a set of 15 bibliographic control characters for use in cataloguing rules, filing rules and indexing rules of the countries and language groups of the bibliographic community. The bibliographic control character set is an extension of the basic control character set defined by ISO 646 (ISO escape sequence ESC 2/1 4/0). 1.2 This International Standard consists of a code table and a legend specifying each bibliographic control character and indicating its code position. In addition, it includes explanatory notes, in which the functional characteristics of the individual control characters are described in detail. 1.3 This bibliographic control character set is primarily intended for the interchange of bibliographic information.