A U-label is an IDN domain name with special characters, such as belgië.be.
The Unicode is an international encoding standard describing a repertoire of characters used to represent most of the world’s languages in written format. The Unicode standard contains tables that list the "code points" (unique numbers) for each local character identified. The collection of scripts used to do this is maintained by the Unicode Consortium.
The Uniform Domain-Name Dispute-Resolution Policy (UDRP) is a process established by the Internet Corporation for Assigned Names and Numbers (ICANN) for the resolution of disputes regarding the registration of internet domain names.