looking up domain names with unassigned code points

Cary Karp ck at nic.museum
Sun May 11 17:13:31 CEST 2008

Quoting Vint:

> technical question:
> if someone generates an arbitrary  string of the form "xn-- <random  
> sequence of lowercase a-z, 0-9 and hyphen>
> does the algorithm ALWAYS produce a sequence of UNICODE code points?  
> Note I did not say a PVALID set of code points or even ASSIGNED.

I'm not sure if or how it weighs into the consideration of this question
but on April 28th, the .SU TLD registry began accepting the
registration of subdomain labels beginning with xn-- without requiring
them to be valid output of the Punycode algorithm:

"A user or service provider can either design software used for
decoding and decoding algorithm on his own or use PUNYCODE algorithm
recommended by ICANN and published in RFC documents."


One purpose of allowing non-IDNA-compliant alternatives appears to be
to permit script mixing:

"In the process of generation of domain names with xn-- prefix using
encoding algorithms mentioned in RFC documents registrators are not
allowed to mix symbols of different national alphabets." 

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