An internationalized domain name (IDN) is an Internet domain name that contains at least one label that is displayed in software applications, in whole or in part, in a language-specific script or alphabet. These would be domain names that are not spelled out in traditional Latin or English character sets, or in traditional ASCII character sets.
Examples include languages such as Arabic, Chinese, Cyrillic, or Latin alphabet-based characters with accents or diacritics, such as French. These writing systems are encoded by computers in multi-byte Unicode. Internationalized domain names are stored in the Domain Name System as ASCII strings using Punycode transcription.
Using IDNs with OpenDNS
If you want to use IDN's with OpenDNS to block/allow a domain in content filtering or search your Reports in the Umbrella Dashboard, you can use a free IDN convertor, such as: http://idna-converter.com/
Simply convert your internalizationed domain name (unicode) into an ASCII/Punycode domain name coverter, and copy the resulting encoded domain into the desired OpenDNS tool.
[credits: Some information taken from Wikipedia]