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Re: Tabindex

From: Al Gilman <asgilman@iamdigex.net>
Date: Mon, 24 Mar 2003 21:05:09 -0500
Message-Id: <5.1.0.14.2.20030324205138.02022080@pop.iamdigex.net>
To: WAI-GL <w3c-wai-gl@w3.org>

At 08:32 PM 2003-03-24, Joe Clark wrote:

> > Proposal:
> > Tabindex can include any number 0 through 9 and may not exceed 32767.  A
> > tabindex of 0 should never be used because the 0 is read as a leading 0
> > as in 03 or 0340.  Therefore a tabindex="0" would be understood as
> > tabindex="" where a tabindex="03" would be understood as tabindex="3".
>
>That is not what the spec says. tabindex="0" is explicitly permitted
>as a legal value.
>
><http://www.w3.org/TR/REC-html40/interact/forms.html#adef-tabindex>
>     2. Those elements that do not support the tabindex
>attribute or support it and assign it a value of "0" are navigated
>next.  These elements are navigated in the order they appear in the
>character stream.
>
>The spec also states "User agents should ignore leading zeros."
>tabindex="0" does not constitute a leading zero. It isn't leading
>anything.

Yes,  TABINDEX='0' functions like TABINDEX="" but no, this is not because it
is treated as a "leading zero."

It is, as Joe reminds us, because TABINDEX='0' is assigned a "none of the
above" reserved value by the spec.  This is like the convention where zero
as the timeToLive is used as a code for "no end in sight."

Authors should be aware that TABINDEX='0' will collate after 32767 and not
before 1.

This is per spec but probably not what they expected.  Merits a warning,
not a prohibition.

Do we say anywhere that TABINDEX should be set on all of the tabbable
elements, or none of them?  The behavior when the elements with TABINDEX set
are walked first and the elements with no TABINDEX set are then walked can
be confusing.  An element with TABINDEX set to zero is just the beginning of
the confusion.

Al


>--
>
>   Joe Clark  |  joeclark@joeclark.org
>   Author, _Building Accessible Websites_
>   <http://joeclark.org/access/> | <http://joeclark.org/book/>
Received on Monday, 24 March 2003 21:03:27 GMT

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