MVALID (was Re: M-Label or MVALID, and dangers with mappings?)

YAO Jiankang yaojk at
Wed Apr 15 07:26:29 CEST 2009

----- Original Message ----- 
From: "Paul Hoffman" <phoffman at>
To: "Andrew Sullivan" <ajs at>; "Pete Resnick" <presnick at>
Cc: <idna-update at>
Sent: Tuesday, April 14, 2009 4:31 AM
Subject: Re: MVALID (was Re: M-Label or MVALID, and dangers with mappings?)

At 12:54 PM -0400 4/13/09, Andrew Sullivan wrote:
>On Sun, Apr 12, 2009 at 02:34:24PM -0500, Pete Resnick wrote:
>> If we're going to deal with mappings, I want it to be a separate
>> document.

>Andrew and Pete: do you feel that it is OK for this WG to update a protocol from one where a conformant application was required to convert "EuroCafé.com" >to a valid DNS request to one where a conformant application can simply reject that input? Note that there is no indication to the user which version of the >protocol is being used.

>You are both fine with that? As you can tell, I am not. 

>I think it is fine for the protocol to reduce the characters that are allowed; I think it is fine to change some >characters mappings when done carefully.

yes, +1

> I think it is not fine to make a mapping that is commonly done by billions of people and silently remove it from the >protocol.


Good protocol design is trying to make people more convenience instead of making people feel more fussy.

Removing the mapping used by billions of people may make many internet users less convenience. We can deal with it but need very careful measures and actions.

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