From: Asmus Freytag (email@example.com)
Date: Fri Aug 17 2007 - 00:34:33 CDT
The corrigendum restores the mirrored property of these quotation marks to the status that they had before Unicode 5.0. (in other words, it reverses a change made in 5.0, which was found to adversely effect existing data). Rather than being troubling, the corrigendum is a welcome correction to a problem that had been introduced in Unicode 5.0.This corrigendum is quite troubling; in a BiDi context, this means that initial quotation marks will not be mirrored.
Anyway, the classification of quotation marks as initial or final is problematic because it is not consistant with actual uses in various languages that use reversed conventions, even in the same LTR directional context and only in the Latin script. So the distinction between "Pi" and "Pe" general categories should remain informative only for the "most common" usage. These punctuations should not be mirrored simply betcause they can't be accurately distinguished asinitial or final. So the exact form (orientation and baseline/exponent position) of these quotation marks should not be altered even in a BiDi context, and it's up to the writer to choose the proper one for each context. But how can you manage the correct reordering of these characters if yoy use them to surround for example a latin quotation within an Arabic text? The initial quotation will need to inherit the directional property from the previous Arabic text, and the final quotation will need to inherit the directional property of the previous Latin text, and there's no way to determine automatically that it should attach here to the Arabic text after it, simply because there's no way to determine if the quotations are initial or final. This is a difficult problem for which there's no clear indication about what can be done exactly on this case where quotation marks are inserted exactly at the positions where a change of script direction occurs. So how to handle this "smartly"? => A good solution will be to consider once again their "Pi"/"Pe" default distrinction in the general category. And in that case, it gives good hints about what the quotations marks are marking. So if you know that a quotation mark is initial or final, then you know that an initial quotation mark after an Arabic text should not be mirrored given that it will be reordered according to the direction of the text after it, and that the finalquotation mark will not need to be mirrored as it will be reordered according to the latin text before it. The Caveat is that an Arabic text will not be able to quote a Latin-written citation »like this« or even ”like that“ even if the quoted language uses this convention (reversed from the default Pi/Pe distinction), but only «like this» or even “like that”. Another difficulty : the quotation marks may be followed by (non-breaking) spaces (this is even mandatory for double angle quotation marks if you use French typography, and depending on tricky typographic differences this may be a NBSP or NNBSP); this is not a major difficulty for the final quotation marks, but will add some difficulty for the initial (Pi) quotation mark in a BiDi context where the embedded quotation needs to be reordered. As a consequence, an Arabic text will not be able to use accurately any (non-breaking) space with the quotation marks to embed for example a French quotation, and so will not accurately cite it using the usual « French » quotation style, unless he drops the non-breaking spaces for «French» or uses the English quotations to embed the “French” citation. Before the corrigendum in Unicode 5, the Arabic text would have needed to embed an Arabic quotation like “Arabic”, but due to the mirrored property, it would have been read with mirrored quotation marks. So an author could have decided to swap his quotation signs into ”Arabic“ (so the initial quotation mark would have the default Pe=ending property, and the final quotation would have the default Pi=initial property) and if he used them as well to cite Latin quotations ”like this“, then the BiDi reordering would still give the expected result because the quotation marks would be attached to the surrounding Arabic text where they are mirrored and not reordered, but not to the inner reordered Latin text which is not mirrored. And after reordering, everybody would see the quoted text as if it was “Latin” with the quotations reordered with the quoted Latin text. After the change, given that the quotation marks are no longer mirrored, the Latin quotation will seem to be now swapped if the text was created for Unicode 5 without the corrigendum (incorrect orientation) in all cases (in an Arabic text, they will look like: .snoitatouq ”cibarA“ dna ”Latin“ erofeb txet emoS This will be the reading of the text rendered by a post-corrigendum renderer from the text encoded in this order: Some text before ”Latin“ and ”Arabic“ quotations. I suppose then that the intent of the corrigendum is to make sure that the quotation marks are not mirrored, given that they were not mirrored in Unicode 4 and before. So the texts are expected to be encoded in this logical order (BiDi reordering and mirroring disabled): Some text before “Latin” and “Arabic” quotations. so that it will be rendered like this in renderers based on Unicode 4 or post-corrigendum Unicode 5: .snoitatouq “cibarA” dna “Latin” erofeb txet emoS but like this if a renderer was built using the pre-corrigendum Unicode 5 properties : .snoitatouq ”cibarA“ dna ”Latin“ erofeb txet emoS There may exist other difficulties for the special case of quotation marks used at the beginning of each paragraph continuing a long quotation (not closed in the previous paragraph) but this will not affect Arabic documents making long Latin quotations, but will possibly affect Latin texts including long Arabic quotations. I think that no authors will try to use this Latin-specific style for long Arabic quotations. (final note: in all I wrote above, replace Arabic by any other RTL script, and Latin by any other LTR script)-----Message d'origine----- De : firstname.lastname@example.org [mailto:email@example.com] De la part de Rick McGowan Envoyé : vendredi 17 août 2007 04:42 À : firstname.lastname@example.org Objet : New Corrigendum to The Unicode Standard The Unicode Consortium has issued a new Corrigendum to The Unicode Standard Version 5.0.0. For details on this corrigendum, see: http://www.unicode.org/versions/corrigendum6.html For general information on corrigenda to The Unicode Standard, see: http://www.unicode.org/versions/corrigenda.html In brief, this corrigendum corrects the Bidi_Mirrored property for several characters. Regards, Rick McGowan Unicode, Inc.
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