Re: [idn] stringprep comment 1

[Paul Hoffman / IMC <phoffman@imc.org>]

At 2:32 AM +0900 1/30/02, Soobok Lee wrote:
>
>In  Stringprep section 6.3,
>
>" Newer stored string -- Suppose that an requesting application is using
>  oldVersion and the stored string was created using a profile that uses
>  newVersion. Because the requesting application passed through any
>  unassigned code points, the user can query on stored strings that use
>  code points in newVersion. No stored strings can have code points that
>  are unassigned in newVersion, since that is illegal. In this case, the
>  querying application has to enter the unassigned code points in the
>  correct order, and has to use unassigned code points that would make it
>  through both the mapping and the normalization steps."
>
>  The old querying application using oldVersion stringprep  *cannot* predict
>
>   1)    the correct order of combining sequences of newly assigned characters
>
>   2)    the  normalized & casefolded form of newly assigned characters.

Correct, but it does not need to, unless the Unicode Consortium goes 
against their promises about how they will handle normalization of 
newly-assigned characters. No new characters will be casefolded.

>  This choices are often IME(platform) dependent and  enforcing such
>    normalized character inputs are  beyond end users' choices and capabilities
>    and also are out of control of independant application authors

Agree. Fortunately, this is unneeded.

>   Non-Unicode legacy IMEs have been producing their own preferred 
>character sequences
>    for new scripts and their 1-1 mapping to new Unicode points may 
>produce unnormalized outputs
>    and they will be fed into old blind applications and make 
>troubles and confusions and failtures.

This makes no sense because new scripts don't have decompositions.

>  Therefore, the last sentence in the cited paragraph does not make 
>sense, IMHO.

It makes sense if you trust the Unicode Consortium to stick to its 
word about newly-assigned characters. If you don't, all of Section 6 
is useless, not just this subsection.

--Paul Hoffman, Director
--Internet Mail Consortium