[Idna-arabicscript] mapping of Full Stops

Vint Cerf vint at google.com
Sun Oct 11 15:15:43 CEST 2009

keep in mind that the Mappings document is NOT normative. It is  
intended to give some ideas for localization and pre-processing. The  
important point is that only U+002E will be recognized in protocol as  
a label separator. For purposes of exchanging IDNs, that's important.  
For local contexts, one might allow alternative full-stop inputs but  
these would need to be converted to the U+002E form prior to  
initiating a DNS query. It would probably be wise also to convert to U 
+002E for purposes of canonical exchange of domain names with other  

For Pete Resnick and Paul Hoffman:

this email might be interpreted as a request to add U+06D4 to the  
Mappings list of potential local mappings to U+002E. Have you an  
opinion whether this edit would be appropriate?


On Oct 11, 2009, at 9:52 AM, Sarmad Hussain wrote:

> In earlier discussions on U+06D4 (ARABIC FULL STOP), which is  
> necessary for Urdu as a label separator (the reasons have been given  
> on this list earlier), it was suggested that the various full stops  
> will not be allowed and be mapped.  It was subsequently requested to  
> include the mapping reference in IDNA200x documents to ensure that  
> the application providers incorporate it, but the request was not  
> considered positively as it was perhaps suggested that such  
> recommendations can not be made part of the protocol.  However, the  
> recent mapping document (http://tools.ietf.org/html/draft-ietf-idnabis-mappings-04 
> ) says on pg. 2:
>   4.  [I-D.ietf-idnabis-protocol] is specified such that the protocol
>        acts on the indvidual labels of the domain name.  If an
>        implementation of this mapping is also performing the step of
>        separation of the parts of a domain name into labels by using  
> the
>        FULL STOP character (U+002E), the following character can be
>        mapped to the FULL STOP before label separation occurs:
>        *  IDEOGRAPHIC FULL STOP (U+3002)
>        There are other characters that are used as "full stops" that  
> one
>        could consider mapping as label separators, but their use as  
> such
>        has not been investigated thoroughly.
> If this is being explicitly done for U+3002, it could be done  
> explicitly for ARABIC FULL STOP (U+06D4) as well. What is the reason  
> for not including other such possible cases explicitly?
> Regards,
> Sarmad
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