Domain names with special characters (IDNs)
- Internationalised Domain Names (IDNs)
- IDNs rules for the .eu and its variants in other scripts
- Homoglyph bundle
- IDNA 2008 protocol
Internationalised Domain Names (IDNs)
Your domain name can contain characters from any official EU language script. These characters include, for example, the Swedish å, the German ü, the Romanian ș and characters from the Bulgarian (Cyrillic) and Greek alphabets as a whole. Domain names that contain these special characters are called Internationalised Domain Names (IDNs).
IDNs are particularly important as the European Union has many languages that have special characters; some European languages use non-Latin scripts (Greek and Cyrillic). EURid has been investigating the IDN environment for almost a decade in partnership with UNESCO, Verisign and the regional ccTLD organisations. The findings of the yearly study are available at idnworldreport.eu
At the top level, EURid manages the .eu extension and its variants in Cyrillic and Greek, .ею and .ευ respectively.
At the second level, IDNs under .eu (or its variants in other scripts) consist of:
- Digits 0 through 9
- Hyphen (-)
- Unicode characters from the Cyrillic, Greek or Latin scripts.
If you would like to register your .eu domain name or its variants in other scripts, click here for a complete list of the supported characters.
It is essential that IDNs behave just like other domain names and work, display and resolve correctly. We call this behavior “Universal Acceptance” or UA, for short. There are still significant barriers to Universal Acceptance of IDNs.
Internet users can still reach any website or email account using the IDN ACE (ASCII Compatible Encoding) string if their browsers or email applications do not support IDNs yet.
IDNs rules for .eu and its variants in other scripts
Script matching at the second level
When you register a .eu domain name, you cannot combine characters from different scripts. All the characters of the domain name at the second level (i.e. the part before the “last dot”) must come from the same script.
The digits 0 through 9 and the hyphen can be used with all Latin, Cyrillic and Greek characters. If you like to register an exclusively numeric domain name - possibly including hyphens – you should specify the extension during registration. In the case that the extension is not specified, the .eu extension (Latin) will be set by default.
Script matching throughout the domain name
The script of the second level domain name must match the script of the extension (ie, Latin .eu, Cyrillic .ею or Greek .ευ). In other words, if the domain name being registered is in Latin script, the script at the top-level will be .eu. On the other hand, if the domain name being registered is in Cyrillic script, the script at the top-level will be .ею.
- How it works
- Homoglyph bundles and .eu extensions
- Managing the activation of equivalent domain names of the same homoglyph bundle
Sometimes, even though a domain name is available, you cannot register it. One of the reasons is that the domain name is included in a so-called homoglyph (from the Greek “homo” = same, and “glyph” = character) bundle.
A homoglyph bundle is a group of domain names of which only the domain name requested first can be registered. The purpose of homoglyph bundling is to prevent lookalike domain names in different scripts from being registered.
Homoglyph bundling contributes to a safer Internet environment by helping to prevent the creation of domain names from two different character sets that are visually indistinguishable and therefore, might lead to confusion among Internet users.
How it works
At the point when a domain name is created, EURid’s automated systems will compare the chosen characters to equivalents in the other supported scripts. A domain name written with Latin characters is compared to the Greek character sets and vice versa. If the systems detect that certain characters are identical or confusingly similar to others, then the domain name is inserted in a homoglyph bundle with the equivalent domain names, which use the identical or confusingly similar characters.
The result of homoglyph bundling is that only one domain name in the bundle is registered and it is not possible to register the others.
Homoglyph bundles and .eu extensions
Homoglyph bundles are applicable to the following extensions:
- .eu (Latin script);
- .ευ (Greek script).
Visually identical or confusingly similar characters across different scripts are bundled.
- Latin a versus Greek α (upper case)
There are exceptions to this rule. Below you can find a non-exhaustive list of characters that are bundled with one another, despite not being visually identical or confusingly similar:
- Latin ß and Latin ss;
- Latin ss and Greek β;
- Greek ς and Greek σ;
- Greek α and Greek ἀ ἁ ἂ ἃ ἄ ἅ and Greek ᾀ ᾁ ᾂ ᾃ ᾄ ᾅ and
- Greek αi and Greek ἀi ἁi ἂi ἃi ἄi ἅi.
Should one or more domain names happen to be part of a bundle but were registered before 6th May 2015, they will continue to be registered. Should they be deleted, they will not be available for new registration and will become “homoglyph blocked” in the EURid web-based WHOIS.
Managing the activation of equivalent domain names of the same homoglyph bundle
A registrant who has registered a domain name belonging to a homoglyph bundle can request that EURid activates one of the equivalent domain names belonging to the same homoglyph bundle.
The newly activated name will be assigned to the same registrant as the previously active one. The domain names cannot coexist, implying that the activation of an equivalent domain name of the same homoglyph bundle will lead to the withdrawal of the previously active domain name.
Registration or related fees for the newly activated domain name will be payable from the moment of activation by EURid and will be invoiced to the registrar according to the current transaction fees. No reimbursement will take place for the initially registered domain name upon withdrawal.
IDNA 2008 protocol introduction
As a consequence of the implementation of the IDNA2008 standard protocol that supplemented the previously deployed IDNA2003 protocol, new characters were introduced to be supported when registering a .eu domain name while others were phased out.
This section aims to explain both the changes from the supported character perspective and the legacy policy for characters or sequences of characters that were phased out.
ß (Latin small letter Sharp S, Unicode U+00DF) and ς (Greek small letter ending Sigma, Unicode U+03C2)
The IDNA2008 protocol supports both the German Sharp S (ß) and the Greek ending sigma (ς) on input as fully allowed characters. Due to the introduction of the homoglyph bundling mechanism, both characters are part of the homoglyph bundling algorithm, meaning that registered domain names containing characters “ss” or the Greek normal sigma (σ) prevent domain names with German Sharp S (ß) or Greek ending sigma (ς) from being registered.
However, considering the limited support of the German Sharp S (ß) and the Greek ending sigma (ς) by many web browsers, a registrant who has registered a domain name containing the characters “ss” or the Greek normal sigma (σ), or vice versa - German Sharp S (ß) or Greek ending sigma (ς) - can request to register also the corresponding domain name at any time. The two names must be assigned to the same registrant. They will coexist and both will be invoiced to the registrar.
EURid regularly checks that the domain names are assigned to the same registrant and if not, revokes the domain name registered by the latter registrant.
EURid continues to investigate and assess the support of the IDNA2008 protocol through the most common client software (web browsers, email clients). When the aforementioned support is deemed sufficient by EURid and the the technical community, the registrant of the domain names for which two “versions” coexist - those with characters “ss”/ German Sharp S (ß) or the Greek normal sigma (σ)/Greek ending sigma (ς) – will be requested to choose which domain name they wish to keep registered. EURid will withdraw the domain name that is going to be blocked by the other name as part of the homoglyph bundle in the usual way.
Registrants of existing domain names with the aforementioned characters - German Sharp S (ß) or Greek ending sigma (ς) - who wish to register the corresponding domain name written with the equivalent characters have to contact their registrar and request registration of the equivalent domain name. The registrar must then send the registration request to EURid and also state that they have received the demand to register the equivalent domain name from the current registrant.
Domain names with hyphens in the second, third and fourth position, or with “ŀ” (L followed by middle dot but not followed by a subsequent L), or with "ı" (dotless i)
.eu domain names that have been registered
- with hyphens in the second, third and fourth position, or
- with “ŀ” (L followed by middle dot but not followed by a subsequent L), or
- with "ı" (dotless i)
are no longer supported.
To allow registrants to seek proper solutions to find possible alternatives, they remained operational for a term of one (1) year and they were phased out on 6th May 2016. Domain names containing the aforementioned characters were revoked and are not allowed for re-registration.