- From: Bless Terje <link@rito.no>
- Date: Wed, 2 Feb 2000 11:19:56 +0100
- To: "'W3C Validator'" <www-validator@w3.org>
Claus Andre Faerber <list-w3c-html-validator@faerber.muc.de> wrote: >Marc A. Donges <marc@kalle.yodanet.schwaebischhall.de> schrieb/wrote: > >>I recently tried to make my documents, which complied with HTML 4.0 >>Transitional, as compatible with XHTML 1.0 as possible (whithout >>switching the DTD yet). > >You can't do this. SGML-based HTML and XHTML use incompatible SGML >declatations (as XHTML is based on XML). To elaborate a bit... * HTML is defined as an application of SGML in a SGML DTD. * XHTML is defined as an application of XML in a XML DTD. One does not modify HTML to be compatible with XHTML. One converts HTML into XHTML and then modifies the XHTML to be (sorta) compatible with HTML _browsers_. The compatibility guidelines in the XHTML 1.0 Reccommendation are to help you make XHTML documents display in today's common browsers the way the HTML document would have, but the document still is XHTML and should include an XHTML DOCTYPE declaration (if it contains one at all; the DOCTYPE is optional in XHTML). The compatibility guideline's reccomendations are intended to fool browsers into thinking the document is "really" HTML and render it. That is the reason why the XHTML 1.0 Reccommendation suggests serving XHTML documents with a MIME type of "text/html" instead of "text/xhtml", "text/xml", or "application/xml" which would be the obvious and, arguably, the correct MIME types. If you did, however, most browsers would offer to save the document to disk because they have not been configured to try to render documents with other MIME types then "text/html". However, where other tools -- such as the W3C HTML Validation Service (which, despite the name, also validates XML/XHTML), authoring and document management systems, workflow managers, etc. -- are concerned, the document is, and must be labeled as, XHTML to be useable. The only reason the compatibility guidelines work at all is that current browsers do not actually contain SGML parsers. If they had, the XHTML 1.0 compatibility guidelines would get you nowhere as browsers would barf on it no matter what you did.
Received on Wednesday, 2 February 2000 05:19:45 UTC