From: Asmus Freytag (firstname.lastname@example.org)
Date: Thu Dec 20 2007 - 02:31:04 CST
adding a LRM or RLM at the head of the paragraph allows the Unicode text
itself to carry an indication of the desired top-level directionality.
That indication will be picked up by any implementation of the *default*
algorithm (but is easily overridden by any external markup in protocols
that support it.). The way it works, is that the mark counts as a letter
with strong directionality, in this case the first strong letter used
for setting the top-level directionality, while being otherwise
invisible in the display.
On 12/19/2007 3:02 PM, Kent Karlsson wrote:
> Stephane Bortzmeyer wrote:
>>> Can't a Hebrew site have a news in Hebrew, with a long quotation of
>>> the speech of an American politician in English in an ltr paragraph?
>> Yes, and Unicode handles it fine, in plain text, without the need for
>> support from a markup language (because each Unicode character has a
> No, that's not the issue. The display of a line of bidi text (with
> actual mix of directions) becomes completely different depending on
> the top level paragraph direction. That is NOT derived from "each
> Unicode character has a direction" (considering just those that
> have strong directionality).
> The initial poster in this thread gave a good example. But here is a
> simpler one, using the convention that uppercase denotes RTL letters.
> The *same* input text, logical order "ABCdefGHI", gets the display
> CBAdefIHG if the top level direction is LTR (a.k.a. level 0)
> IHGdefCBA if the top level direction is RTL (a.k.a. level 1)
> The top level paragraph direction is not inherent in the text (and
> *cannot* be), though the bidi algorithm specifies a default, but just
> a default, usually overriden by markup (or language tag) when markup
> (or language tag) is available, since the default is not stable for
> editing (unless the editor forces the use of a LRM or RLM char at the
> beginning of each paragraph).
> /kent k
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