Re: Need for Level Direction Mark

From: Kent Karlsson <>
Date: Thu, 15 Sep 2011 00:42:38 +0200

Den 2011-09-14 19:56, skrev "Philippe Verdy" <>:

> 2011/9/14 Kent Karlsson <>:
>>> And how will you define what is an "implicit" LDM ? For example "1.2"
>> Did you actually READ my submission re. the PRI? Seems like not. There is a
>> suggestion there (which requires a bit of character contextual processing).
>> It is also possible to use a different analysis for special cases, e.g.
>> domain names or URLs (if detectable somehow, e.g. via markup).
> Yes I have read it, and I'm convinced this will not work. It breaks
> the UBA in a non-conforming and incompatible way. I'm now sure that
> LDM is not even needed if the UBA is implemented correctly.

Note that my suggestion was aimed at a possible UBA v.2 (which is option 3
in the PRI). UBA (v.1) would be unchanged. It is not the case that all bidi
control characters can be avoided in all cases using my suggestion. But
a great many cases, many that surprise users, would with the implicit bidi
control approach work with much less surprise, and no need to insert
explicit bidi controls (something which is not so easy).

Back to the original issue of this thread: All the workarounds w.r.t. LDM
depend on the directionality of neighbouring characters, not directly on
the embedding level direction. Therefore I think none of them will work
properly in all cases (even though they may give the seemingly correct
result in many cases). And they all require an inordinate amount of
insertion of bidi control characters. (Much better to have *fewer* bidi
control characters and still get a desirable display.)

    /Kent K
Received on Wed Sep 14 2011 - 17:47:56 CDT

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