Nameprep: A Stringprep Profile for Internationalized Domain Names (IDN)

Abstract

This document describes how to prepare internationalized domain name (IDN) labels in order to increase the likelihood that name input and name comparison work in ways that make sense for typical users throughout the world. This profile of the stringprep protocol is used as part of a suite of on-the-wire protocols for internationalizing the Domain Name System (DNS).

Internationalized Domain Names in Applications (IDNA): Protocol

“…This document does not update or alter the Punycode algorithm specified in RFC 3492 in any way. RFC 3492 does make a non-normative reference to the information about the value and construction of the ACE prefix that appears in RFC 3490 or Nameprep [RFC3491]. For consistency and reader convenience, IDNA2008 effectively updates that reference to point to this document.…”

Review and Recommendations for Internationalized Domain Names (IDNs)

“…RFC 3491 Nameprep: A Stringprep Profile for Internationalized Domain Names (IDN) [RFC3491]. Nameprep is designed to meet the specific needs of IDNs and, in particular, to support case-folding for scripts that support what are traditionally known as upper-and lowercase forms of the same letters.…”

“…Organizations that took specific positions a year or more ago might not make exactly the same statements today. IDNA, through its requirement of Nameprep [RFC3491], uses equivalence tables that are based only on the characters themselves; no attention is paid to the intended language (if any) for the domain name. However, for many domain names, the intended language of one or more parts of the domain name actually does matter to the users.…”

PRECIS Framework: Preparation, Enforcement, and Comparison of Internationalized Strings in Application Protocols

“…The Stringprep framework was developed during work on the original technology for internationalized domain names (IDNs), here called "IDNA2003" [RFC3490], and Nameprep [RFC3491] was the Stringprep profile for IDNs. At the time, Stringprep was designed as a general framework so that other application protocols could define their own Stringprep profiles.…”