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[idn] IDNs do not use ASCII
- To: idn@ops.ietf.org
- Subject: [idn] IDNs do not use ASCII
- From: "D. J. Bernstein" <djb@cr.yp.to>
- Date: 10 Aug 2001 17:19:35 -0000
- Automatic-Legal-Notices: Copyright 2001, D. J. Bernstein. My transmission of this message to you does not constitute a copyright waiver or any other limitation of my rights, even if you have told me otherwise.
- Mail-Followup-To: idn@ops.ietf.org
Keith Moore writes:
> > > addresses are defined to be ASCII in both RFC 822 and RFC 2822
> > Wake up, Keith! We're changing this definition.
> get back on your meds, Dan. IDN is *not* changing the format of addresses
> used in any protocol, with the possible exception of DNS.
On the contrary. IDN is replacing ASCII with another character encoding
in every Internet protocol that uses domain names.
The ASCII standard specifies, for example, that the byte string bq--blah
(i.e., \142\161\055\055\142\154\141\150) represents characters bq--blah.
Under a typical ACE IDN proposal, however, that byte string represents a
different sequence of characters, and there's another byte string that
represents the characters bq--blah.
Sure, ASCII and ACE both use 7-bit bytes; this doesn't mean that ASCII
and ACE are the same! A character encoding is not a set of byte strings;
it is a _mapping_ between character strings and byte strings.
---Dan