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Re: Specifing language direction in RDF

From: Chris Croome <chris@webarchitects.co.uk>
Date: Fri, 1 Mar 2002 18:46:12 +0000
To: www-rdf-interest@w3.org
Message-ID: <20020301184612.GB9252@webarchitects.co.uk>
Hi

On Fri 01-Mar-2002 at 08:05:53 -0500, Lars Marius Garshol wrote:
> 
> So it seems that you have a property derived from the XHTML 'dir'
> attribute which associates the string "ltr" with your abstract.
> Formally that looks like perfectly OK RDF to me. The property you use
> also seems reasonable, though http://www.w3.org/1999/xhtml#dir might
> be better.

Yes I did wonder about that, http://www.w3.org/1999/xhtmldir, seems
wrong, but can/should one use http://www.w3.org/1999/xhtml# for the
XHTML namespace?

> An obvious question is whether there's any point in doing this at all.
> English written in the latin script is *always* LTR, so you are adding
> no useful information.

Yes I know that :-)

The reason that I was having a play with ltr, rather than rtl, is that I
can't write any rtl languages... 

I'm anticipating that I'm going to be asked by a client to set up a web
site with Arabic and Urdu content and this will result in Dublin Core
RDF metadata files that have a mixture of directionality and wasn't sure
how to implement the advice from the W3C and Unicode consortium [1],
thats why I posted to this list.

> In fact, the only time when you really do neeed to specify text
> direction is when you are mixing LTR and RTL text in the same string,
> which is most likely going to be an extremely rare occurrence. As long
> as all of the text is in the same direction the default text
> directions specified by the Unicode standard should cause display
> engines to do things correctly.
>
> In fact, the only reason you will ever need to specify a direction is
> so that the bidi algorithm will know what the base direction for the
> string/paragraph is. That can't be determined from the text
> automatically (when the text is in more than one direction), and so
> needs to be provided by a human. This is the only thing you actually
> need to specify direction explicitly (in this way) for.

If it doesn't need to be specified in RDF files than that suites me
because it'll make things a lot easier.

The reason I wasn't sure that specifing the directionality was
unnecessary was from an experiment in which I took a Hebrew [2] and a
Farsi [3] file from the Unicode web site, removed all HTML and CSS
directionality markup and then opened them in mozilla, the Farsi one
still displayed the text correctly but the Hebrew one was backwards. 

Is it not safer to specify the directionality in markup, just in case? 

> | Is this the right way to specify the direction of text in RDF?
> 
> It seems reasonable to me.

Great :-)

Chris


[1] http://www.w3.org/TR/2002/NOTE-unicode-xml-20020218/#Bidi

[2] http://www.unicode.org/unicode/standard/translations/hebrew.html

[3] http://unicode.org/unicode/standard/translations/persian.html 

-- 
Chris Croome                               <chris@webarchitects.co.uk>
web design                             http://www.webarchitects.co.uk/ 
web content management                               http://mkdoc.com/   
everything else                               http://chris.croome.net/  
Received on Friday, 1 March 2002 13:45:36 GMT

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