Re: [idn] case folding

[Harald Tveit Alvestrand <Harald@Alvestrand.no>]

At 08:39 31.05.2000 -0400, Brian W. Spolarich wrote:

>   I guess I'll be a contrarian today.

welcome to the club!


>   In looking over the RFC index, I see a lot of examples of protocols that
>tend towards case-insensitivity as the default for comparisons.  These
>protocols also tend to do this in the context of plain ASCII characters
>(i.e. LDAP v3, RFC2251).  I haven't seen a lot of examples of
>case-insensitivity in larger character sets, precisely because of the
>complexity involved that we're talking about here.

the least unreasonable treatment I know of in an IETF protocol is one shown 
in ACAP, RFC 2244, section 3.4, which defines an extensible set of 
"comparator" functions. An UNICODE-TR21 comparator might be an useful addition.
I believe the inspiration came from LDAP, which, however, ties the 
comparator to the datatype.

>   What problem does case folding solve?  Is it reasonable for protocol
>users to expect that MYDOMAIN.COM and MyDoMaIn.CoM are semantically the
>same, and therefore the protocol should understand that?  While there is a
>backward compatibility requirement for US-ASCII, is it truly the case that
>users of the IDN will so strongly expect this behaviour that it becomes a
>requirement?  Is it possible to come up with a case-folding implementation
>that is going to satisfy the behavioural expectations of the large
>majority of the users?  I am mostly ignorant of these issues as they apply
>to the the vast majority of languages, but given the issues that have been
>raised here, I have to wonder if this is practically achievable.

I too wonder.

                      Harald

--
Harald Tveit Alvestrand, EDB Maxware, Norway
Harald.Alvestrand@edb.maxware.no