Unicode Explained

use. You could for example allow 8-bit characters in headers when posting to Usenet

but disallow them in email.

It is not possible to give a comprehensive presentation of the ways that email programs

should be configured and used with regards to character encoding. The discussion in

this section is meant to present the basics for an analysis of the various settings that are

available in each program. The bottom line is that anything beyond ASCII in message

headers may cause problems, though modern email programs usually understand

whatever another modern email program sends.

Characters in Domain Names and URLs

The use of the Web and the Internet in general has become more genuinely global and

multilingual than it used to be. This has made it more obvious that we need possibilities

for using non-ASCII characters in URLs (web addresses) as well as in Internet domain

names. These two are somewhat connected, but not the same thing. You could have a

domain name like école.example that you wish to use in different contexts, such as email

addresses. You could also wish to use a URL like http://école.example/Noël where you

have a non-ASCII character not only in the server part (the domain name) but also

elsewhere.

Internet domain names, especially those of web servers, have become very important

in business. Companies typically advertise their web sites by printing the domain name

in their brochures ...