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WCAG 2 comments follow-up

From: Carlos Iglesias <carlos.iglesias@fundacionctic.org>
Date: Mon, 24 Mar 2008 13:05:03 +0100
Message-ID: <09700B613C4DD84FA9F2FEA5218828190320E4B9@ayalga.fundacionctic.org>
To: <public-wai-ert@w3.org>

You can see WCAG WG response on the "80 characters per line" [1] and the "user agent role on SC" [2] issues.


- Regarding the 80 characters per line issue, I don't see any change in the updated technique they refer to [3] in comparison with the one I was talking about [4]. Not sure whether they send the wrong URI or I'm not explaining myself correctly.

They say the requirement is that line length can be set to 80 characters or less by resizing the browser window, not that they be 80 characters or less in all circumstances, but my point is that the only way to achieve this is using always percentage unit for width setting in every block of text.

The suggested technique of using ems to set the column width so that lines can average 80 characters or less is not valid because:

* Em measure refers to font height, not width

* Font width is not predictable and differs from font to font. It typically ranges from 1/3 to 2/3 the font height (em), but may also be outside this range.

* You can use the most restrictive prediction and bet for 1/3 using a 27 (1/3 of 80) ems width limit (not the 50 or 80 the technique suggests), this will give you about 40 characters per line in fonts closer to the 2/3 limit, probably a less than acceptable measure as not many characters per line equally affects readability, and still can't be sure how this will affect to fonts outside the given range.

* You will be limited to use the same font family and size along the same column or try to calculate the equivalences between them, probably an impossible task if you need some sort of precision in the result, even far from pixel perfection.


- With respect to those SC where the user agent may play a role, I agree with them in the fact that techniques may be a better place for this kind of comments, but don't see any example of them there as they say.


[1] - [http://lists.w3.org/Archives/Public/public-comments-wcag20/2008Mar/0092.html]
[2] - [http://lists.w3.org/Archives/Public/public-comments-wcag20/2008Mar/0093.html]
[3] - [http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS/C20.html]
[4] - [http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS-20080310/C20.html]

Regards,
 CI.

__________________


Carlos Iglesias

Fundación CTIC
Parque Científico-Tecnológico de Gijón
33203 - Gijón, Asturias, España

teléfono: +34 984291212
fax: +34 984390612
email: carlos.iglesias@fundacionctic.org
URL: http://www.fundacionctic.org 
Received on Monday, 24 March 2008 12:05:22 GMT

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