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Re: Success criteria 1.4.4

From: Ramón Corominas <listas@ramoncorominas.com>
Date: Sun, 30 Oct 2011 14:38:02 +0100
Message-Id: <5C8E6329-B6C4-4AA4-9AA9-86B3938CC1AF@ramoncorominas.com>
To: "w3c-wai-ig@w3.org" <w3c-wai-ig@w3.org>
Hi all!

While re-reading this thread, I noticed this sentence from Felix:

"One need only raise the size of a 16px font to about 22.4px to get a doubling of size. A doubling of a CSS "size" produces an nominal _size_ increase of 400%."

This seems to consider "size" as the *area* of the block of text, which would imply that an "increase of 200%" means "original font-height * sqrt(2)"; but according to the Understanding SC 1.4.4 document:

"Content satisfies the Success Criterion if it can be scaled up to 200%, that is, up to twice the width and height."

I've always interpreted that 200% means "original font-size * 2", but some customers use the "area" argument to reduce the impact of this requirement on their CSS, because "size" is not explicitly defined in the WCAG's main document.

On the other hand, the Understanding document also says:

"The author cannot rely on the user agent to satisfy this Success Criterion for HTML content if users do not have access to a user agent with zoom support. For example, if they work in an environment that requires them to use IE 6 or Firefox."

This may suggest that, for a *global* scenario (where we cannot guarantee what UA is used), using absolute units for text size can be considered a failure of SC 1.4.4. But then it would be very easy for the WAI WG to include a Common Failure in the Techniques document saying that absolute units are not valid.

I've alwayd interpreted that the absence of such faikure in WCAG 2.0 means that absolute units are not strictly prohibited, unless they cause overlapping/hidden content (F69, for example).

My concern is that, if I consider the Understanding as an "informative only" document, then the 200% is still subject to interpretation; but if I consider the 200% definition in the Understanding as *the* -mandatory- definition, then the absolute units shoukd also be considered as a direct failure.

What do you think?

Regards,
Ramón.


Felix wrote:

> One need only raise the size of a 16px font to about 22.4px to get a doubling of size. A doubling of a CSS "size" produces an nominal _size_ increase of 400%.
Received on Sunday, 30 October 2011 13:36:00 GMT

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