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Re: [Issue 512] Seeking lower bound on text size requirement

From: Martin Duerst <duerst@w3.org>
Date: Mon, 21 May 2001 15:49:57 +0900
Message-Id: <>
To: Ian Jacobs <ij@w3.org>, clilley@w3.org
Cc: w3c-wai-ua@w3.org, w3c-i18n-ig@w3.org
Hello Ian,

Just a few thoughts:

- There is two issues of resolution, namely a) the screen resolution
   (in pixels) and b) the visual resolution (in terms of optical frequency
   per degree angle measured from they eye.

   For a), certain scripts may need more pixels for character height
   (or width) than others. As the Latin script is rather at the lower
   end (for upper-case only, a height of 5 pixels is enough), you won't
   get i18n problems, I guess (e.g. if the details for your checkpoint
   say: "...control...size...of text down to at least 5 pixels...",
   then that won't make it impossible for other scripts to get to their
   smallest feasible size). In other words, a tight (i.e. as high as
   possible) lower bound requirement can differ for different scripts,
   but you can just take the minimum, and the minimum for Latin is a
   good overall minimum.

   b) is more difficult, because the UA software doesn't really control it.

- Being able to increase the reference size of rendered text can also be
   an I18N issue, as for some scripts, you really want to make the reference
   size larger.

- The hight should be the overall hight, not the x-height. The aspect
   ratio doesn't have anything to do with it as far as I understand.

- Please note that there are programs (mostly layout software such
   as pagemaker,...) that show a line of text below a certain size as
   a grey strip. This is called 'greek text' (as always, typographers
   use strange terms :-). This can be quite helpful to get an overview
   of a large page, less disturbing that actual text that is too small
   to be read, but I'm not sure it's an accessibility issue.

Regards,  Martin.

At 11:21 01/05/18 -0400, Ian Jacobs wrote:
>Chris, Martin,
>The UAWG would like your input on a question of visual text
>rendering and internationalization. Checkpoint 4.1 of the 9 April
>2001 draft [1] starts:
>   "4.1 Allow global configuration and control over the reference
>        size of rendered text ..."
>This is a Priority 1 checkpoint. One reviewer pointed out that it
>is not really a P1 requirement to allow the user to choose very
>small text sizes. Indeed, the intention of this checkpoint is
>primarily to allow users with low vision to increase text
>size. [I would note here that small text is useful to some users
>(e.g., so that users with screen readers can scroll less), but
>that's not a P1 requirement.]
>At our teleconference yesterday we asked ourselves whether we
>could come up with some lower bound on the requirement. Thus,
>user agents would not be required to provide access to very
>small text size as part of meeting this checkpoint (or,
>for example, they might allow configuration, but not
>actually be required to render very small text).
>Our questions are thus:
>  - How might we express a lower bound in text size?
>    What units would we use? What parameter to measure
>    size (x-height? aspect ratio?)?
>  - What internationalization issues enter into this
>    discussion? Does a lower bound requirement
>    make sense across different scripts?
>Thank you for your help on this topic,
>  - Ian
>Note to the Working Group: For checkpoints 4.1 and 4.2, we should
>change "rendered text" to "visually rendered text" to be more
>[1] http://www.w3.org/TR/2001/WD-UAAG10-20010409/
>[2] http://server.rehab.uiuc.edu/ua-issues/issues-linear-lc3.html#512
>Ian Jacobs (ij@w3.org)   http://www.w3.org/People/Jacobs
>Tel:                     +1 831 457-2842
>Cell:                    +1 917 450-8783
Received on Monday, 21 May 2001 03:19:32 UTC

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