Re: [idn] ToUnicode output can be longer than input

[Dan Oscarsson <Dan.Oscarsson@kiconsulting.se>]

Adam M. Costello wrote:

>> Maybe IDNs, as that is a construct of IDNA, but not domain names in
>> general.  Domain names in an international context is not defined by
>> IDNA,
>
>The *representation* of domain names in an international context is not
>defined by IDNA, but IDNA does define a mechanism for deciding which
>names are valid in that context, and does define a way to compare names
>in that context.
>
>The IETF could produce a second set of definitions in the future, but
>until that happens, the IDNA definitions provide the only standard way
>to use non-ASCII characters in domain names, even in an international
>context.

Unless I remember wrong, IDNA defines a way to compare names in ASCII
context because it requires names to be in IDNA ACE format.
Comparing names in an international context must be done using
UCS characters directely.

At the moment, unfortunately, IDNA restricts the way domain names can
be written and what characters can be used, partly due to its way
to handle domain names in legacy protocols. It was possible to handle
it better, but was not chosen so.

I do not want to limit domain names, in an international context, because
of a legacy compatibility issue.

   Dan