--On Wednesday, February 11, 2015 18:59 -0700 Peter Saint-Andre
- &yet <[email protected]> wrote:
>...
> How's this?
> The authors of a profile might believe that they need to
> define a new directionality rule of their own. Because of the
> complexity of the issues involved, such a belief is almost
> always misguided, even if the authors have done a great deal
> of careful research into the problems of displaying
> bidirectional strings. This document suggests that profile
> authors who are thinking about defining a new directionality
> rule think again, and instead consider using the "Bidi Rule"
> [RFC5893] (for profiles based on the IdentifierClass) or
> following the Unicode bidirectional algorithm [UAX9] directly
> (for profiles based on the FreeformClass or in situations
> where the IdentifierClass is not appropriate).
Wfm.
> One thing that bothers me here is that we're not providing
> actionable guidance to the vast majority of non-delusional
> profile authors. Are we saying that it's not a good idea to
> say anything about directionality at all?
I think I don't understand what you are saying/ asking for. It
seems to me that every version of the statement posted to the
list in the last 24 hours has said things that come down to:
(1) Directionality can be tricky. (not actionable, but
important context)
(2) If you have something identifier-like, use 5893 unless you
know better.
(3) If you have something more free form-like, use UAX #9 unless
you know better.
(4) If you think you know better, you are probably wrong; see
above.
(2) and (3) are, AFAICT, about as actionable as things get,
representing clear statement of the character of "if <condition>
then do this..." The "unless you know better" statements and
(4) is a warning about (2) and (3) to avoid our getting too
normative about situations we can't anticipate
The only substantive difference I've seen in the various
statements is whether the equivalent to (3) suggests saying as
little as possible about FreeformClass.
I'd rather we didn't, but the above could be restated in
2119-speak as:
(2) If you have something identifier-like, you SHOULD use 5893.
(3) If you have something more free form-like, you SHOULD use
UAX #9.
(1) and (4) Directionality is tricky. If you have specific
knowledge of the characters or script(s) you are using that the
contexts in which they are used, you MAY invent your own
techniques and specifications, as allowed by the above.
However, there is considerable experience to indicate that you
should not do so unless it is also absolutely necessary because
you are likely to get it wrong and, even if you don't, adopting
rules different from 5893 or UAX 9 is likely to confuse and
irritate users.
john
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