RFC 3491 (rfc3491) - Page 2 of 7

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

RFC 3491                      IDN Nameprep                    March 2003


   -  The mappings used: specified in section 3.

   -  The Unicode normalization used: specified in section 4.

   -  The characters that are prohibited as output: specified in section
      5.

   -  Bidirectional character handling: specified in section 6.

1.1 Interaction of protocol parts

   Nameprep is used by the IDNA [IDNA] protocol for preparing domain
   names; it is not designed for any other purpose.  It is explicitly
   not designed for processing arbitrary free text and SHOULD NOT be
   used for that purpose.  Nameprep is a profile of Stringprep
   [STRINGPREP].  Implementations of Nameprep MUST fully implement
   Stringprep.

   Nameprep is used to process domain name labels, not domain names.
   IDNA calls nameprep for each label in a domain name, not for the
   whole domain name.

1.2 Terminology

   The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
   in this document are to be interpreted as described in BCP 14, RFC
   2119 [RFC 2119].

2. Character Repertoire

   This profile uses Unicode 3.2, as defined in [STRINGPREP] Appendix A.

3. Mapping

   This profile specifies mapping using the following tables from
   [STRINGPREP]:

   Table B.1
   Table B.2

4. Normalization

   This profile specifies using Unicode normalization form KC, as
   described in [STRINGPREP].







Hoffman & Blanchet          Standards Track