Different Bidirectional Character Types

[r12a]

Does this help clarify the original question?

Modern Standard Arabic: Expressions & sequences
https://r12a.github.io/scripts/arabic/arb.html#expressions

  see also
https://r12a.github.io/scripts/arabic/block.html#ar061C

ri

Asmus Freytag via Unicode wrote on 06/07/2022 02:44:
> On 7/3/2022 2:20 AM, Andreas Prilop via Unicode wrote:
>> On 3 July 2022, Eli Zaretskii wrote:
>>
>>> I thin UAX#9 clarifies it perfectly: numbers are displayed in LTR order.
>> This is undisputed.
>> I ask about the differences
>>
>>    “555-2368” vs. “2368-555”
>>
>>       “1=3−2” vs. “1=2−3”
>>
>> “1999-12-31” vs. “31-12-1999”
>>
>> The Bidirectional Algorithm is responsible for these differences. But why?
>
> The real answer is that this matches differences in displaying lists 
> of numbers (!) not order of digits, in Hebrew vs. Arabic.
>
> The Bidi algorithm uses the classes AL and AN (and rules that resolve 
> them) to implement these inherent differences in the way the various 
> scripts handle such cases (multiple groups of digits separated by punct).
>
> As I mentioned, I raised a public review issue to make sure that UAX#9 
> either *specifically and explicitly* cites or, alternatively, 
> incorporates language that explains scripts have different preferences 
> in resolving groups of numbers (not: digits) and points in a high 
> level to where in the spec these preferences are addressed.
>
> I agree, it's not enough to reverse engineer the algorithm and 
> conclude that it behaves as specd. It should be a simple matter to 
> understand why it was designed the way it was.
>
> A./
>

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