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RE: XHTML Basic and XHTML modularization: ACRONYM and BDO

From: Jonathan Rosenne <rosenne@qsm.co.il>
Date: Tue, 22 Feb 2000 23:47:48 +0200
To: Nir Dagan <nir@nirdagan.com>, Jonny Axelsson <jonny@metastasis.net>, www-html@w3.org
Message-id: <NDBBIFGHGLJILJGHOEELMEPKCEAA.rosenne@qsm.co.il>
To put it in different words: In terms of Unicode, BDO is the equivalent of
LRO/RLO, while SPAN with dir is the equivalent of LRE/RLE, and dir for block
level elements specifies the base direction.

Jony


> -----Original Message-----
> From: www-html-request@w3.org [mailto:www-html-request@w3.org]On
> Behalf Of Nir Dagan
> Sent: Tuesday, February 22, 2000 6:34 PM
> To: Jonny Axelsson; www-html@w3.org
> Subject: Re: XHTML Basic and XHTML modularization: ACRONYM and BDO
>
>
> At 01:59 PM 2/22/00 +0100, Jonny Axelsson wrote:
> ...
> >And as for BDO, what is the point with the BDO element, given that every
> >applicable element, in particular SPAN, has a DIR attribute? What
> >advantages has
> >
> ><p><bdo dir="rtl">right to left text direction here.</bdo></p> to
> ><p dir="rtl">right to left text direction here.</p>?
> >
> >(substitute any other element for P as needed)
> >
>
> The bdo element and the dir attribute on other elements do completely
> different things.
>
> <bdo> says that characters should be shown in a particular directionality
> disregarding the bi-directional algorithm. The dir attribute in other
> elements (not in BDO) sets the directionality of neutral characters,
> such as spaces, in order that the browser will apply the
> bidirectional algorithm
> to the whole thing correctly. Thus, the dir attribute has
> different semantics
> in BDO and other elements.
>
> That is <span dir="rtl">Nir</span> should be rendered as Nir
> (as there are no neutral characters in the <span> at all; Latin
> characters
> are all left to right.)
> and <bdo dir="rtl">Nir</bdo> should be rendered as riN. (It
> doesn't matter that
> these are Latin characters; as the directionality is overridden)
>
> An argument in your favor is that the functionality of BDO is available
> via special bi-di override characters that are a part of HTML's
> character set.
>
> An argument in favor of <bdo> is that if you write "by hand",
> that is in a regular text editor, it is very easy to make mistakes
> of improper nesting. With <bdo> a validator will catch many of
> these errors. With special characters, SGML validators don't
> help for this problem. Special characters are good for
> sophisticated editing Unicode bi-di aware software (which doesn't
> really exists as of now).
>
> Last thing. I actually agree on the ACRONYM ABBR thing. Even if they have
> different semantics, in practice they are used inconsistently by
> different
> authors, in a way that makes them practically equivalent, say for default
> styling by browsers or for general indexing robots.
>
> Regards,
> Nir.
>
> ===================================
> Nir Dagan
> Assistant Professor of Economics
> Brown University
> Providence, RI
> USA
>
> http://www.nirdagan.com
> mailto:nir@nirdagan.com
> tel:+1-401-863-2145
>
Received on Tuesday, 22 February 2000 16:49:30 GMT

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