Most domain names contain only the characters a-z, 0-9 and hyphens, but what do you do if your company is called “Björns Åkeri” or "Guðrún's Icelandic horses"? With the help of IDN, the Internationalized Domain Names, you can use an increased number of characters in addition to the regular character set of the DNS system.

Many people want to be able to express their identity or brand with their own language on the internet, and a website can feel more consistent if the domain name is written in the same language as the content of the page.

The Domain Name System (DNS) only allows the characters a-z, 0-9 and hyphens, but through IDN, the Internationalized Domain Names, you can use different types of special characters in domain names. This is done with ACE (ASCII Compatible Encoding) which uses a special prefix; xn--, in front of encoded IDN domain names (for example xn--smrgs-pra0j.se for smörgås.se).

IDN support at .se and .nu

It is up to those responsible for each top-level domain to select the characters that they want to support from the greater amount available in Unicode. Since .se it should be the obvious choice on the internet for everyone with a connection to Sweden, we think it is important to be able to express their identity with us also in the official minority languages. This is an important step in increasing the diversity of the internet.

An .se domain may contain, in addition to the DNS system’s character set, å, ä, ö, ü and é, the Nordic languages writing characters, and all the characters in the official Swedish minority languages (Finnish, Meänkieli (Tornedals Finnish), Sami, Romani and Yiddish). A complete list of all the characters that can be used in .se domains can be found in this character table.  

A .nu domain may contain, in addition to the DNS system’s character set, å, ä, ö, ü and é, as well as a large number of writing characters in the western European languages and the other Nordic languages supported. A complete list of all the characters that can be used in .nu domains can be found in this character table.

To manage IDN domains in DNS, these domain names must be re-encoded so that they contain only the allowed characters.

You do not have to do this yourself, but it is done automatically when you register your IDN domain with any of the The Swedish Internet Foundation’s resellers (registrars).

So far, not all retailers have support for IDN. To find out who supports IDN, you can filter the list by checking “Offers IDN domain name registration”.

Variable software support for IDN

Newer versions of the most common web browsers have IDN support by default, so you don’t have to worry about losing visitors to your site if you use special domain names. However, it is currently only a few e-mail programs that support IDN domain names and in most cases, it is not possible to write directly with special characters in the on or off field of e-mail messages. However, one can use the ACE-encoded representation of an IDN name in common email programs. However, this does not mean that the programs support IDN in the part of the address that is to the left of the at sign (@) in the email address. It is a functionality that is not yet available.

All software where domain names are used, not just web browsers and email programs, must be upgraded to be able to read and convert the encoding into understandable words. Our recommendation is that anyone who wants to register an IDN domain should also have a classic domain name as a complement. In addition, there are still many Internet users who do not have the software needed to enter an IDN domain, or even manage to enter the name of their keyboard.

Expand the number of special characters

Those responsible for each top-level domain select the characters they find a reason to support from the greater amount available in Unicode. The Swedish Internet Foundation has plans to increase the number of characters supported so that we can handle many other languages used by large groups of the population. However, when this is done, it has not been decided and the timetable has not been clarified.   

There are a number of good reasons to proceed carefully. Perhaps the most important thing is that once we have opened the opportunity to register new characters, it is basically impossible to reverse the decision. A mistake could therefore prove to be fatal and an expensive lesson.

The Swedish Internet Foundation also does not want to see a special Swedish solution, but has actively participated in the standardization work in order to be able to agree on an international standard for managing national characters in domain names.

With different solutions in different parts of the world, at worst, DNS can break down. This will in turn make the addressing on the internet ineffective when problems arise between such different applications running on the same computer, different operating systems and different types of devices (computer, mobile phone and other Internet connected devices). For multinational companies and organizations, the problems would be obvious.