I've like many been keeping an eye on XML and XSLT. It seems to me, that the high interest in these technologies suffers from an astonishing blind spot : reversibility. XML and XSLT are viewed as the perfect data "tubing", that will finally allow easy integration of multiple data sources. XSLT is a powerful tree transformation language, that seems up to the task to enunciate any transforms between two equivalent XML-dressings of data. I believe a very desirable but completely overlooked feature of output styling, is REVERSIBILITY OF TRANSFORMS. I see two typical forms of uses for such a feature. (a) Wysiwig editing of styled output, with deconstruction and back-propagation of the updates to the store. (b) Networking data stores, again with backpropagation of distributed updates to the distinct mother store of each data item. I believe there may be long-term "second niche" for Zope with (b), and a more immediate opportunity with (a)... At a glance, (a) means opening a new model for web-based data acquisition, one that acknowledges that HTML forms weren't designed to provide superslick click-and-point, and, instead of trying to beat MS IE on its own ground, takes another road : have the app serve model documents that the user can modify with a wysiwig html editor (e.g. Amaya), and PUT back... whereupon the app (e.g. Zope) would parse the modifications and distribute them back where they belong... or return the same page, with red annotations for what doesn't parse. Couple motivational notes : (i) Of course, the design of an extensive "reversible style sheet" language is no small matter. But start in the small : think of the situation where one notices a mistaken digit in a figure in a web page. If the page is automatically generated and styled from a data store, wouldn't it be nice (and shouldn't it be possible !) to tell the system : "update the item from which that digit was obtained" - without further ado (except where security is concerned). (ii) There is a parallel to make, between the Closed/Open Source duality, and the Mono-/Bi-directional stylesheet issue, on the other hand. Bidirectional style-sheets are like open source, since they make it easier for the final consumers of data, to effect changes at the source of the data. (iii) Last week, someone posted the open source announcement of Xanadu/Unadax; from what I could gather at their site, their critique of current web technology parallels the above proposal. (iv) XLST doesn't beat DOM in the heart of many "procedurally minded" developpers; and indeed, the DOM is much more flexible. Bidirectionality is where a declarative language like XSLT could really excel. I write this thinking of the recent praise for XMLDocument; somebody spoke of the simplicity of using DTML for XML styling, as compared to XSL; this means that DTML is currently competing with XSL in zopeland, and there may exist a temptation for Zope development to continue on that lead. What I am saying, is that bidirectionality of transforms (which neither XSLT or DTML currently have) is a better ground to be critical of XSLT, since this is where XSLT's declarative style of programming should be stronger. Boris Borcic