Q3: What characters should be allowed in a revised IDNA2008 specification?

Vint Cerf vint at google.com
Tue Mar 31 18:14:24 CEST 2009

IDNA2008 currently allows a more restricted set of characters to be  
used in domain name labels than IDNA2003 does.

Does the working group agree that the more restricted set of the  
current IDNA2008 Tables document should apply once IDNA2008 is  
adopted? What should be done about registrations that use characters  
that would not be allowed under IDNA2008? Should there be a  
transitional period of finite duration after which these registrations  
will become invalid? Should they be grandfathered somehow? If we  
believe all future registrations should be restricted, how would such  
grandfathered registrations be found if the IDNA2008 rules would  
reject lookups of the disallowed characters?

A two-lookup scheme might solve this problem:

1. lookup according to IDNA2008 rules (if disallowed characters are  
present, go to step 2); if domain name record is found, return the  
information. If not, go to step 2
2. lookup according to IDNA2003 rules (permitting a broader range of  
characters in the lookup process). If domain record is found, return  
it, if not return "no such domain name"

Vint Cerf
1818 Library Street, Suite 400
Reston, VA 20190
vint at google.com

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