Re: Need for Level Direction Mark

From: Philippe Verdy <>
Date: Tue, 13 Sep 2011 15:01:57 +0200

2011/9/13 Richard Wordingham <>:
> This is a summary of what I have already submitted for Public Review
> Issue 205 (  I am mentioning it
> here in case there is something wrong with my idea.
> My basic idea is that one does not a 'level direction mark'.  The
> desired effect can be achieved by embedding neutrals in a sequence
> LRM...RLM or RLM...LRM.  They will then take on the directionality of
> the embedding by Bidi Rule N2.
> For an example, see my submission.  It may be helpful to view the source
> of the full page view, for that has examples in HTML written solely in

Your example for reversing the direction of fields in notations like "
1.2.3 " where the dot should be interpreted as a number separator and
not a decimal separator does not seem to work: instead of seeing "
3.2.1 " when you use RLM, I read " 3 2.1." in a LTR context ;
something may be wrong in the Bidi algorithm or in its implementation
on Windows when using Uniscribe (in Chrome), or in the browser itself.

I don't know how you can avoid using either Bidi controls (which
ones?), or an equivalent CSS property on spans in HTML, or new
characters with another Bidi class... CS characters are clearly
ambiguous(and this includes the dot, slash, plus, minus, colon,
comma...). Just consider also maths notations, these characters used
as operators do not always allow commutativity of operands (this is
the case also when formatting dates and times).

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).
Received on Tue Sep 13 2011 - 08:05:18 CDT

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