[Typo3-dev] FYI: Internationalized Domain Names (IDN)

[Martin T. Kutschker]

Hi!

Some facts on the subject. For those who want to work on coding 
regarding them.

The main problem I see for a complete implementation, that PHP lacks the 
functions to perform the necessary Unicode normalization. But it's 
possible to do this with pure PHP (invloves generating mapping tables 
out of Unicode data files).

Note: the algorithms work on Unicode code points, not iso-8859-1, etc.

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http://www.unicode.org/unicode/reports/tr15/tr15-22.html
Unicode Standard Annex #15 - Unicode Normalization Forms

http://www.ietf.org/rfc/rfc3454.txt
Preparation of Internationalized Strings ("stringprep")

  Normalization: none or KC (see "Unicode Normalization Forms")

http://www.ietf.org/rfc/rfc3491.txt
Nameprep: A Stringprep Profile for Internationalized Domain Names (IDN)

  Mapping: table B.1 and B.2 (see "stringprep")
  Normalization: KC
  Prohibited Output: table C.1.2, C.2.2, C.3 - C.9
  Bidirectional characters: checking required
  Unassigned Code Points in IDNA: table A.1

http://www.ietf.org/rfc/rfc3490.txt
Internationalizing Domain Names in Applications (IDNA)

  Required standards: "nameprep" and "punycode"
  ACE prefix: xn-- (case insensitive)

http://www.ietf.org/rfc/rfc3492.txt
Punycode: A Bootstring encoding of Unicode
  for Internationalized Domain Names in Applications (IDNA)

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Masi