Using XSL Formatting Objects for Production-Quality Internationalized Document Printing

The XSL Formatting Objects (XSL-FO) specification was designed from the start to be locale and language neutral. This makes XSL-FO well suited to the task of composing for print internationalized documents, and in particular, documents in non-Western languages. However, users of XSL-FO are dependent on both the implementation of XSL-FO internationalization features, such as support for different writing modes, as well as on implementation of locale-specific composition functions, such as line breaking, hyphenation, and glyph shaping. Users of XSLFO that use XSLT to generate FO instances are also dependent on the ability to do locale-specific processing within the XSLT transform, including the localization of generated text strings and locale-specific sorting for back-of-the-book indexes. This paper evaluates the XSL 1.0 specification and the currently-available implementations against the composition requirements of internationalized documents, including Arabic, Hebrew, Thai, and other Asian languages. It discusses the various challenges inherent in the production of documents in non-Western languages and the XSLT and XSL-FO facilities available for meeting those challenges. We then report our experience in using XSL-FO with commercial and open source tools to produce localized hardware user manuals for a line of consumer computer peripherals. We discuss the XSLT and XSL issues, as well as XSL-FO extensions that may be required to satisfy typical print production requirements. Finally, we provide a set of recommendations, based on the current state of the XSL specification and the current state of tools, as to when the use of XSL-FO is appropriate and which XSL-FO implementations are best suited to which tasks or disallowed by certain sets of requirements.