Internationalized Domain Names in Applications (IDNA): Protocol

The Network Access Identifier

“…In order to ensure a canonical representation, characters of the realm portion in an NAI MUST match the ABNF in this specification as well as the requirements specified in [RFC5891]. In practice, these requirements consist of the following item:…”

“…When the realm portion of the NAI is used as the basis for name resolution, it may be necessary to convert internationalized realm names to Punycode [RFC3492] encoding form as described in [RFC5891].…”

A GSS-API Mechanism for the Extensible Authentication Protocol

“…When comparing the host portion of a GSS-EAP acceptor name supplied in EAP channel binding by a peer to that supplied by an acceptor, EAP servers SHOULD prepare the host portion according to [RFC5891] prior to comparison. Applications MAY prepare domain names prior to importing them into this mechanism.…”

The Unicode Code Points and Internationalized Domain Names for Applications (IDNA)

“…It should be noted that NFKC is used, although Normalization Form C (NFC) is used in the "IDNA Protocol" document [RFC5891].…”

“…That information appears in the Protocol document [RFC5891], but it is important to understand that the assignment of a value of this property to a particular character is not sufficient to determine whether it can be used in a given label. In particular, some combinations of allowed code points are not advisable for use in IDNs due to rules specific to a script or class of characters.…”