Re: Need for Level Direction Mark

From: Asmus Freytag <>
Date: Tue, 13 Sep 2011 07:54:29 -0700

On 9/13/2011 6:01 AM, Philippe Verdy wrote:
> Unfortunately, adding controls would imply the creation of new Bidi
> classes for them (and forgetting the stability policy about them,
> which was published too soon before solving evident problems).

The first part is correct, and giving up stability to that degree would
be a serious issue.

I disagree with the second part. True plaintext bidi will always be a
compromise, because there's a lack of information on the intent of the
writer. (In rich text, you can supply that with styles). There's a
limited workaround with bidi controls, but that's beginning to be a form
of minimal rich text in itself.

Stability is paramount for predictability. You need to be able to
predict what your reader will see, and you will only be able to do that,
when you can rely on all implementations agreeing on the details of how
to lay out bidi.

Introducing any new feature now, will result in decades of
implementations having different levels of support for it. This makes
the use of such a new feature unpredictable - and is a problem whether
there was a formal stability guarantee or not.

Received on Tue Sep 13 2011 - 09:58:48 CDT

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