The design goal of [NAMEPREP] is to allow users to enter host names in applications and have the highest chance of getting the name correct. The NAMEPREP process comprises of three basic steps, namely "MAP", "NORMALIZATION" and "PROHIB".
The MAP and NORMALIZATION step aims to reduce the number of possible representations domain name that should be equivalent. These are based upon Unicode Technical Reports [UTR15] and [UTR21]. However, when there are multiple representations of the same domain name but matching changes depending on languages and context, NAMEPREP will fail in these cases. Of our interest, Traditional and Simplified Chinese ideograph cannot be handled by NAMEPREP.
ノーマライゼーション (スコア:2, すばらしい洞察)
3.2. NAMEPREP
The design goal of [NAMEPREP] is to allow users to enter host names in applications and have the highest chance of getting the name correct. The NAMEPREP process comprises of three basic steps, namely "MAP", "NORMALIZATION" and "PROHIB".
The MAP and NORMALIZATION step aims to reduce the number of possible representations domain name that should be equivalent. These are based upon Unicode Technical Reports [UTR15] and [UTR21]. However, when there are multiple representations of the same domain name but matching changes depending on languages and context, NAMEPREP will fail in these cases. Of our interest, Traditional and Simplified Chinese ideograph cannot be handled by NAMEPREP.
とのことだそうです。参考までにUTR15 Unicode Normalization FormsとUTR21 Case Mappingsです。(すみません、こっちもろくに読んでません。)
というわけで、各国の状況を知る必要はないでしょうが、Unicode ってじつはバグバグだったりする部分もあるし、改定やバグフィックスは大いにありうるので、そのときに、それに追随するのか規格として固定したままにするのか、見ものですな。
それにしても、中国語がだめだとか書いてあるなあ...