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Re: Liaison statement on fragment identifiers from Linking WG

From: Bill Smith <bill.smith@sun.com>
Date: Tue, 18 May 1999 02:40:53 -0700
Message-Id: <199905180947.CAA505373@jurassic.eng.sun.com>
To: shane@themacs.com
Cc: shane@themacs.com, Tim Bray <tbray@textuality.com>, Steven Pemberton <Steven.Pemberton@cwi.nl>, w3c-xml-cg@w3.org, w3c-html-wg@w3.org, www-html-editor@w3.org, w3c-xml-linking-wg@w3.org
At 09:10 AM 5/17/99 -0500, Shane P. McCarron wrote:

>I think you have a misunderstanding of how this technology works.  In
>general, the transition from HTML to XHTML requires well formedness and
>using both name and ID attributes on certain elements. Such a strategy
>guarantees that XHTML will work in HTML 4.0 conforming browsers. After
>all, HTML 4.0 stipulates that the ID and NAME attributes share a
>namespace.  Therefore, any document that was HTML and is converted to
>XHTML will continue to work, and conforming browsers will continue to
>resolve fragment references correctly.
>
>What may not work is if the conversion were to remove the name
>attributes from these elements. This is because older or broken HTML 4.0
>browsers sometimes do not use the id attribute. Consequently, we need to
>leave it in. Maybe what we should also do is deprecate it in XHTML 1.0
>so that the transition strategy is clear?
>

It may be that I misunderstand how this technology works but I fail to see
how HTML tidy, when run over a single document instance, will cause all
referring URLs (from other documents) to be properly updated. A simple
example:

  In HTML 4.0 the following is legal:
    <A NAME="bill's-address">

  In XHTML 1.0 this becomes (with the help of a tool like HTML tidy)
    <A NAME="bill's-address" ID="bill-0039s--address">

I've used "-" as an escape character in this example. It's a valid
character in attribute values of type ID and should allow us to manually
translate CDATA NAME atribute values to ID ID attribute values. If I've
thought about this correctly, I now have a document instance that can be
served as HTML or XHTML. 

But all of the documents that refer to this document instance will still
have fragment IDs of the form "bill's-address" and these fragment IDs will
fail when the resource retrieved is of type XML - unless some form of
fallback to HTML 4.0 behavior is specified for all XML.

Basically, the transition (for fragments IDs) from an attribute of type
CDATA to one of type ID will be problematic unless XML-generic processing
of these fragment IDs follows HTML 4.0 specific semantics. Webs of
documents will possibly cease to function properly when the conversion
occursor at some point in the future after everyone working on the
conversion has moved on.
Received on Tuesday, 18 May 1999 05:47:47 GMT

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