Please respond to "Nadav Har'El" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
To: Tzafrir Cohen <[EMAIL PROTECTED]>
cc: Ely Levy <[EMAIL PROTECTED]>, [EMAIL PROTECTED]
Subject: Re: official hebrew in Linux-IL mailing lists?
Nadav Har'El wrote the following about Unicode Bidi algorithm, some of
which is not correct.
>Almost, but not exactly. The problem is that Unicode doesn't specify the
>major direction of the text. A plain-text file doesn't have any direction
>queues besides the text itself (assuming it doesn't contain special LRM
>codes, etc.) so when I wrote bidiv (for example) I found myself having to
>invent heuristics (paragraphs seperated by an empty lines, etc. - we
talked
>about that in ivrix-discuss).
Unicode states that in the absence of a higher protocol, the major
direction (called "paragraph imbedding level") is set according to the
first strong character. In that respect, LRM is no better or worse than
a, b or c.
>What if my heuristics are different from those used by Microsoft? What
>heuristics do the KDE or Gnome mail programs use when showing a
Hebrew/English
>email to determine the main direction of a line?
According to Unicode, the paragraph embedding level is computed anew for
each block. A block is delimited by the start/end of text, and by Block
Separators. There are no Block Separators within ISO-8859 code pages. It
would be up to applications to recompute the direction for each line, or
sentence, or paragraph or whatever units make sense for them.
>I guess that to be really sure how your text is displayed, you must start
>each sentence with a unicode direction character.
Sentences have no particular role in the Unicode algorithm. An
application can give them a role for direction determination, but data
interchangeability would need all connecting applications to apply the
same logic.
>But these are not available
>in ISO-8859-8-i, which most Hebrew email and text files have been written
>with so far.
If you consider LRM/RLM as direction characters, they do exist in
ISO-8859-8
Shalom (Regards), Mati
Bidi Architect
Globalization Center Of Competency - Bidirectional Scripts
IBM Israel
Phone: +972 2 5870999 ext. 1202 Fax: +972 2 5870333 Mobile:
+972 52 554160
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