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Subject: Re: [dita] [dita-translation] TC/DITA/Translation Subcommittee Proposals
Gershon L Joseph wrote: > 1. The Unicode standard defines a default direction for each language. For > example, for English this default direction is LTR and for Hebrew it's RTL. To expand on Gershon's explanation a little bit: The directionality is actually defined for each character (not the language, as Unicode doesn't deal directly with languages but rather with scripts (that is, when Unicode talks about "Arabic" they mean the script named Arabic, not the language Arabic, which happens to use the Arabic script). For most languages there is a direct mapping to a script (but not always, although those cases usually fall outside the set of languages used for technical publications). Thus, while we usually informally talk about "languages" when dealing with things at the character level we usually really mean "scripts". With respect to controlling (or not controlling) directionality, in addition to the cases where you have to adjust the default directionality is the case where you have characters that are naturally paired and that, by default, are rendered to reflect the current directionality, i.e., parens "(" and square brackets "[". For example, given this source data: <p>(arabic characters)</p> The rendered result would be: (sretcarahc cibara) not: )sretcarahc cibara( However, when the parens contain or are adjacent to left-to-right characters then things can get confused (and confusing). I've seen this most when you have numbers or latin-script words embeded in right-to-left text within parens, i.e.: <p>arabic characters (XSL-FO) arabic characters</p> In this case the directionality of the enclosing Arabic characters causes the parens to be "flipped", giving results like this: sretcarahc cibara )XSL-FO( sretcarahc cibara or sretcarahc cibara (XSL-FO( sretcarahc cibara This can be addressed by using LRO or RLO characters or by using LRE or RLE (left-to-right embedding and right-to-left embedding) characters in the input data stream. However, this is complicated by the fact that many tools do not implement the Unicode bi-di rules correctly. In particular we found that tools that rely on the Windows libraries for doing right-to-left rendering give different results from tools (mostly FO implementations) that implement the algorithm themselves (and presumably better). However, the algorithm is difficult enough to understand that its hard to prove that a given implementation is or isn't correct. So you are often faced with just hacking the source data until you get the result you want. In my work with rendering Hebrew and Arabic technical documents where the translators are creating the non-English text *and* they can't modify the markupm their only option is to add the actual Unicode characters to the data stream (which they can always do). Cheers, Eliot -- W. Eliot Kimber Professional Services Innodata Isogen 9390 Research Blvd, #410 Austin, TX 78759 (512) 372-8841 ekimber@innodata-isogen.com www.innodata-isogen.com
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