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Question about px: Relative size?

From: Sailesh Panchang <sailesh.panchang@deque.com>
Date: Thu, 21 Apr 2005 12:34:11 -0400
Message-ID: <001b01c5468f$f27d6920$a201a8c0@deque.local>
To: <w3c-wai-ig@w3.org>, "WebAIM Discussion List" <webaim-forum@list.webaim.org>, "Tim Boland" <frederick.boland@nist.gov>
Tim and all,
 I note from the W3C doc on basic data types in CSS2  (1) that  Relative units include:
px: pixels, relative to the viewing device 
"Pixel units are relative to the resolution of the viewing device, i.e., most often a computer display. If the pixel density of the output device is very
different from that of a typical computer display, the user agent (browser) should rescale pixel values."

Is there a difference in terminology here? Ppixels are
relative/scalable in regards to "physical" viewing devices, as are em & % units. But the following: "Make content scalable by using relative measures like em, px, percentages for specifying characteristics like sizes, width,
etc." could lead a developer to believe that their text will be scalable, or rather sizable, within the content when viewed in a browser. While this is true with em & % units, it is not with px, right?
One can scale fonts by allowing them to change the size  through the browsers text size feature.  The pixels units do not allow that. So is px "relative"?
*1: http://www.w3.org/TR/1998/WD-css2-19980128/syndata.html
*2: http://lists.w3.org/Archives/Public/w3c-wai-gl/2004JanMar/att-0247/wcag728.htm

Thanks much,
Sailesh Panchang
Senior Accessibility Engineer 
Deque Systems,11180  Sunrise Valley Drive, 
4th Floor, Reston VA 20191
Tel: 703-225-0380 Extension 105 
E-mail: sailesh.panchang@deque.com
Fax: 703-225-0387
* Look up <http://www.deque.com> *

Received on Thursday, 21 April 2005 16:39:50 UTC

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