Where DSSSL Fits In
It is no exaggeration to say that DSSSL (pronounced dissle) is complex. To do anything serious with DSSSL you need a fair familiarity with not just the programming language LISP, but a specific dialect of LISP called Scheme. You could probably cram the world's supply of Scheme programmers into one small room.
It isn't easy to learn DSSSL because there's next to no documentation other than the drafts of the ISO standard. In June 1997 a volunteer project to create a DSSSL handbook was begun on the DSSSL Internet mailing list, the address of which is given in Appendix B, but it hasn't produced much so far (volunteers are welcome).
The complexity of DSSSL (compounded by the fact that it describes two languages and not just one-the transformation language and the style language) very quickly led to an attempt to create a simplified version called DSSSL-Lite. DSSSL-Lite, in its turn, gave rise to an Internet variation of DSSSL called DSSSL-o (short for DSSSL-online).
The very first version of the XML style language (then called XS) was based very heavily on DSSSL-o, and the available DSSSL-o software was slowly being adapted to accommodate XS, which made migration very simple.
XS was adapted, HTML additions were brought in to make it more compatible with existing CSS styles, and a lot of the DSSSL-o features were removed. The syntax was radically different, but the conceptual model was still the one inherited from DSSSL. This all resulted in the first version of XSL.
In August 1998, a revised and very incomplete revision of the language was released as a Working Draft. This version of XSL still uses the same processing model as DSSSL but, again, the syntax is radically different. New software tools are already starting to appear (you will learn to use the first of them on Day 20, "Rendering XML with XSL"), but it is clear that it will be quite some time before XSL has stabilized and even longer before it is widely supported by tools and browsers.
XSL is still in a state of flux. Meantime, DSSSL hasn't gone away and the jade package is just as good as it ever was. If anything, it just goes from strength to strength because the latest release (1.2) includes a mif backend that can convert SGML and XML code (and therefore, by definition, HTML code too) into the Maker Interchange Format. The Maker Interchange Format that can be read directly by Adobe's FrameMaker and Frame+SGML high-end DTP software packages.