The W3C (World Wide Web Consortium: http://www.w3.org), which is an organization for standardization pertinent to WWW (World Wide Web) technology, provides for the descriptive language for representing structured documents, such as CSSI (Cascading Style Sheets, level 1:http://www.w3.org/TR/REC-CSS1) or CSS2 (http://www.w3.org/TR/REC-CSS2).
Typical of the descriptive languages for structured documents are HTML (HyperText Markup Language), SGML (Standard Generalization Markup Language) and XML (eXtensible Markup Language). Of these, XML features the user being able to define tags as necessary, in distinction from HTML allowing for use only of pre-defined tags.
The above-mentioned customary descriptive languages are all designed on the basis of documents written in horizontal array, and hence may be difficult to use in vertically arrayed texts, such as those written in Japanese or Chinese. For example, if it is desired to represent the vertically arrayed document in “upward-justified” style, a command for “left justification” needs to be used as a command, despite the fact that the conventional descriptive language based on the horizontally arrayed text “upward-justifies” the vertically justified text, thus imposing difficulties in understanding on the user.
There is a layout descriptive command specialized in vertical text arrangement, such as “upward justification” or “downward justification”. However, if this command is used, mere attempt to represent the structured document in horizontal text arrangement leads to the necessity for re-writing the totality of the layout-related information.