XHTML2 and "current browsers" (Was: Re: [XHTML2] Unicode line and paragraph separators)

On Sunday, Apr 6, 2003, at 00:30 Europe/Helsinki, Tantek elik wrote:

> People will write XHTML2 that "happens to work" in current/legacy 
> browsers
> that don't actually have any support for XHTML2, kind of like people 
> are now
> writing/sending XHTML1 that "happens to work" in current/legacy 
> browsers
> that don't actually have any support for XHTML1.

XHTML2 WD 6 says:
"However, thanks to XML and stylesheets, such strict element-wise 
backwards compatibility is no longer necessary, since an XML-based 
browser, of which at the time of writing means more than 95% of 
browsers in use, can process new markup languages without having to be 
updated. Much of XHTML2 works already in existing browsers."

The claims about compatibility with current browsers seem incompatible 
with XHTML2 being in its own namespace and not intended to be delivered 
as text/html.

Current browsers have no idea about the upcoming XHTML2 namespace. 
Therefore, as far as the current browsers are concerned, XHTML2 is just 
some arbitrary XML stuff that doesn't have anything to do with XHTML1. 
The current browsers don't come with a meaningful UA style sheet for 
XHTML2. To some extent, current browsers allow arbitrary XML to be 
presented with CSS. However, there are important behaviors (eg. 
followable hyperlinks) that can't be associated to arbitrary XML using 
standard CSS. The author would have to ship a non-standard CSS+XBL+JS 
implementation of XHTML2 with every document. Besides, CSS is supposed 
to be optional, so relying on CSS to bind meaningful behaviors to an 
unknown (to the browser) type of document tree is not a robust solution.

And that's assuming XHTML2 is served as application/xml or 
application/xhtml+xml. If XHTML2 is to be delivered using a new content 
type, the current browsers won't even attempt to process the documents 
beyond handing them to a helper app.

So in what sense does any part of XHTML2 "happen to work" in any 
current browser? Also, what's the technical basis of the claim "Much of 
XHTML2 works already in existing browsers." in the working draft?

Henri Sivonen

Received on Saturday, 12 July 2003 06:17:28 UTC