Microsoft, Inso, ArborText propose style sheet language for XML

October 20, 1997

Seybold Report on Internet Publishing
Vol 2, No 2

Interest in Extensible Markup Language (XML), or simplified SGML, continued last month as a contingent of vendors, led by Microsoft, proposed to the World Wide Web Consortium a style sheet language for XML documents. The new style language complements XML, which is a way to make Web documents with user-defined tags.

Called XSL (Extensible Style Language), the new style language offers more capabilities than the present cascading style sheet specification for HTML. XSL adds provisions for formatting of elements based on their position in the document, handling of generated text and defining formatting macros. It also introduces an extensible set of formatting objects, and is notable for being the first Web style sheet language that accommodates languages (e.g., Hebrew, Arabic) that flow in directions other than from right to left.

Although it goes beyond CSS, XSL is being developed so that its style sheets can be easily translated to CSS for HTML documents.

XSL, drafted by representatives from Microsoft, Inso and ArborText, is a subset of the Document Style Semantics and Specification Language (DSSSL), which was developed as a complement to SGML. Not coincidentally, Microsoft enlisted the aid of SGML expert James Clark, one of the architects of DSSSL, to help write the XSL specification. Sharon Adler, editor of the DSSSL standard and a co-author of XSL, said that the DSSSL committee will work to develop revisions to DSSSL that keep it a compatible superset of XSL.

There is much that XSL does not provide. It lacks many specific features one might want to see in a print style sheet (e.g., multiple columns, widow and orphan control, and so forth), but its rules-based approach to formatting on the fly is an exciting new development in Web publishing. It will enable an XSL-capable browser to perform simple tasks—such as rearranging elements and reformatting them accordingly—that previously could only happen on the server. And XSL will bring new capabilities, such as adjusting box rules to the dimensions of the type composed within the box, that are not possible in HTML today. Fortunately, it includes HTML/CSS flow objects, which will ease the transition from CSS to XSL and make HTML output an easy target for XML documents and XSL styles.

For publishers that already use SGML, the rapid pace of XML-related development and Microsoft’s noticeably strong interest in it are welcome changes from the past decade, when SGML was relegated to a niche supported only by small software suppliers or by small pockets within larger developers. Though the first XML implementations will likely focus on data processing, not on document formatting, the introduction of a Web style sheet language for XML looks promising as the foundation for richer online style presentations in the future.

At this point, the W3C has not formally adopted the proposal, but we hope that it will, and that other vendors will adopt it and participate in its improvement. The industry has been waiting long enough for a neutral style sheet language that vendors could implement. DSSSL proved to be too hard; a simpler subset that applies the principles of rules-based formatting to the Web (which right now needs it more than print) makes a whole lot of sense.

The XSL proposal can be found on the Web at: XSL at W3C