[idn] Interactions between short-term and long-term

["D. J. Bernstein" <djb@cr.yp.to>]

Paul Hoffman / IMC writes:
> Am I missing some significant effect that ACEs might have on other 
> long-term solutions?

Yes. If we allow ACE-based IDNs, then we'll have to keep them working
during the subsequent transition to UTF-8.

Consider, for example, franXais.com, but with c-cedilla in place of X.
Someone registers the ACE version of this. We make the huge changes
required for ACE. Users can then send mail to franXais.com.

Then we switch to UTF-8. There's a transition period where some clients
send ACE franXais.com and some clients send UTF-8 franXais.com. Both of
these will have to work! The registrar and domain owner have to copy all
their ACE data to UTF-8 data, and make subsequent changes in both forms.

The costs of this duplication aren't present in the initial move to ACE.
They also aren't present in a direct move to UTF-8. They're extra costs
of a transition. An initial move doesn't have to keep old IDNs working;
a transition does.

---Dan