TRIROFF, an Adaptation of the Device-Independent TROFF for Formatting Tri-directional Text

This paper describes a system for formatting documents consisting of text written in languages printed in three different directions, left-to-right, right-to-left, and top-to-bottom. For example, this paper is such a document because it contains text written in English, Hebrew, Japanese, and Chinese. The system assumes that the input is in the order in which the text is read aloud, and it produces output in which each language is printed in its own correct direction, but for which a human cognizant of the reading conventions will reproduce the input order. The system consists of three major pieces of software: Ossana and Kernighan’s ditroff for formatting text consisting of only left-to-right or unidirectional text, Buchman and Berry’s ffortid for rearranging right-to-left language text buried in ditroff output to be printed from right to left, and a new program bditroff for arranging that top-tobottom text buried in ditroff output is printed from top to bottom. Below are translations of this English language abstract, except for this paragraph, into Hebrew, Japanese, and Chinese. The latter two are each printed twice, once in a modern leftto-right style, and once in a more traditional top-to-bottom style. The software described in this paper was used to format and typeset this paper.