Re: [idn] Requirements I-D

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

At 5:40 AM -0400 5/17/00, John C Klensin wrote:
>I don't believe, for reasons that others have explored on the
>list, that a "case-folding algorithm" (in the "drop one bit in
>ASCII" sense) is feasible.  Instead, one would need mapping
>tables and would need to understand that some of the "foldings"
>are not reversible (e.g., ones that remove accents or
>diacriticals when going from "lower case" to "upper case".

Agree.

>Those mapping tables would presumably need to be updated each
>time a character was added to the code set, so they had probably
>best be embedded in the DNS files/tables or, at worst, in the
>servers -- if every client machine on the network needs to be
>updated each time new characters are added, I think we have a
>non-solution.

Another option is to say that we will not add any more case-folding 
after the original set is defined. To the best of my understanding, 
none of the scripts to be added to ISO 10646 are both (a) in common 
use and (b) require case-folding. This is not to say that we must do 
it at the client, but to say that given the maturity of the current 
10646 repertoire, we could.

>I'm also concerned about the problem that acceptable
>mapping/folding rules may differ from locale to locale with the
>same characters.  Perhaps that is in the "bad, but not terrible"
>category, but what this is supposed to be all about is letting
>people use their own characters and languages in natural ways.

For some value of "natural". Today's ASCII case-folding is not 
natural for many novice users, but they are being taught that it is 
just the way that it is. When we expand the characters involved with 
the beginning of IDN, there will be new rules that users have to get 
used to.

Regardless of where the conversion is done, it should not be done in 
a locale-dependent way unless we want to have two users at different 
locations get different results for the same query, or the same user 
giving the same query at two different places getting different 
results. Neither of those would count as "natural" to many users.

--Paul Hoffman, Director
--Internet Mail Consortium