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RE: Fw: putting reader text in hidden <div> tags / adding pauses

From: Phill Jenkins <pjenkins@us.ibm.com>
Date: Mon, 3 Dec 2001 15:47:40 -0600
To: w3c-wai-ig@w3.org
Cc: "Mike Scott" <mscott@msfw.com>
Message-ID: <OF78A216A6.2B2165E5-ON86256B17.00759A4A@raleigh.ibm.com >
Mike, Charles, and others
the "presentation modes" Charles referred to in the CSS spec are referring
to "media types".  Screen readers today are reading the "visual" media type
[CSS+HTML].  If the author marked the "visual" information as hidden, the
screen reader should respect that attribute.  The "Aural" media type, if
ever supported by screen readers, does not tell the screen reader what to
do with interpreting the "Visual media" attributes.  I do not agree with
the private interpretations that somehow suggest that media types are
referring to presentation instructions for screen readers.  Even if a "self
voicing browser" [not a screen reader] supported all the media types, the
spec does not define what to do other than the assertion that the user
agent itself decides which media types it supports.  For example, Home Page
Reader supports the media group "visual", so it must honor the visibility:
hidden attribute.  This should be something discussed further in WCAG 2.0,
the Device independent working group, or a new working group for screen
reader developers.

Media types are explained in CSS at
http://www.w3.org/TR/REC-CSS2/media.html

The difference I understand between display: none and visibility: hidden is
what I call "white space".  Display: none creates no white space, no
formatting space or box, [nothing is there], while visibility:hidden
creates a space, but it is empty.  Not sure if there is any difference when
it comes to a screen reader.

Mike wrote:
> "Skip Navigation" links are perfect examples of items that we might want
> hidden but definitely should be read by a screen reader. (Instead of the
> current work arounds like invisible images or text set to the same color
> as the background.)

There is a design debate about "definitely" as in definitely hiding the
"Skip navigation" link.  It could be just some small text that is visible.
But the reason we recommend the "current work around" [alt text on
invisible images] is because it works! And it has to when CSS it turned
off! Visibility: hidden wouldn't work with CSS off.

> Also, there could be cases where dynamically hidden
> elements (such as pop-up or expanding/collapsing menus) also should be
> read.

This is exactly why screen readers should NOT read text that is hidden by
JavaScript.  By honoring the visibility properties affected by JavaScript,
the JavaScript page can be made directly accessible and - more importantly
- usable.  For example, web applications "hide" content when it is not
pertinent to the user's profile.  Blind users should not be forced to read
all the hidden content, usually out of order and context,  when the sighted
users doesn't have to.

Regards,
Phill
Received on Monday, 3 December 2001 16:47:58 GMT

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