Making progress on the mapping question

Vint Cerf vint at
Mon Mar 30 13:41:49 CEST 2009

There has not been any significant objection to the proposals made  
during the IETF 74 meeting to apply some form of mapping during  
lookup. The two questions outstanding are:

1. what mapping function should be used?
2. how should it be used

As Harald and others have observed, if it is applied before an  
IDNA2008-style lookup, we will not find new characters permitted under  
IDNA2008 if they happen to be mapped under IDNA2003. This seems to  
argue for:

1. first look up under IDNA2008 rules
2. If a domain name is found, return the corresponding results
3. If a domain name is not fund, apply IDNA2003 mapping
4. If a domain name is found, return the results
5. If a domain name is not found, report that no such domain name exists

One final point. It seems to me that we should put the IDNA2003  
mapping function into stasis, making no future changes to it, and use  
the IDNA2008 framework to accommodate any new additions into Unicode  
versions as they are released. Assuming we have ample warning of a new  
version, we can even prepare tables suited to the new release ahead of  
time so as to have them available at the point where a new version of  
Unicode is adopted.

Could the WG please analyze this proposition, point out flaws and  
suggested corrections for them?



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

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