Learning XML, 2nd Edition

Chapter 8. Presentation Part II: XSL-FO

XSL-FO rounds out the trio of standards that make up XSL. The FO stands for Formatting Objects, which are containers of content that preserve structure and associate presentational information. XSLT prepares a document for formatting using XPath to disassemble it and produce an XSL-FO temporary file to drive a formatter.

Under a W3C charter, the XSL Working Group started to design a high-powered formatting language in 1998. XML was still new, but XSL was understood early on to be a factor in making it useful. The group split its efforts on two related technologies, a language for transformations (XSLT) and another for formatting (XSL-FO). XSLT, the first to become a recommendation in 1999, demonstrated itself to be generally useful even outside of publishing applications. XSL followed as a recommendation in 2001.

Cascading Style Sheets, a jewel in the crown of the W3C, had been around for a few years and was a strong influence on the development of XSL. Its simple but numerous property statements make it easy to learn. You will see that quite a few of these properties have been imported into XSL-FO. The CSS box model, elegant and powerful, is the basis for XSL-FO’s area model. Mostly what has been added to XSL-FO are semantics for handling page layout and complex writing systems.

The principal advantages of XSL over CSS are:

• Print-specific semantics such as page breaking. CSS happens to be moving in this direction too, so this distinction is ...