Abstract: A document processing apparatus has a printer for printing characters; a keyboard used for inputting characters such as alphabetical characters, symbols and numerical characters; attribute imparting circuitry for imparting an attribute to characters input by the keyboard so as to vary the character spacing of the characters; and a pitch control circuit for varying the character pitch in accordance with the attribute imparted by the attribute imparting circuitry to cause the printer to print the characters at a varied character pitch. Accordingly, it is possible to print a numerical expression while providing suitable spacings between adjacent alphanumerical characters and between one or such characters and any adjacent symbol.

Abstract: Disclosed is a novel print element for a serial impact printer having a novel character set which permits the typing of text as well as chemical symbols and formulae with a small number of character elements. Closed ring structures may be formed with the character set which may be expanded to various sizes. Also disclosed is a serial impact printing system using the aforementioned printing element which automatically subscripts small numerals when the printing element is positioned without further action on the part of the typist.