Definitions limit on label length in UTF-8
Shawn.Steele at microsoft.com
Mon Sep 14 21:58:52 CEST 2009
You're suggesting some smaller # of Unicode characters? Are you counting in UTF-16?
From: Vint Cerf [mailto:vint at google.com]
Sent: Monday, September 14, 2009 12:42
To: Shawn Steele; idna-update at alvestrand.no
Subject: Re: Definitions limit on label length in UTF-8
Expressing limits in unicode characters (code points) regardless of coding
scheme seems like a useful way to offer insight for implementers. V
----- Original Message -----
From: idna-update-bounces at alvestrand.no <idna-update-bounces at alvestrand.no>
To: idna-update at alvestrand.no <idna-update at alvestrand.no>
Sent: Mon Sep 14 12:59:08 2009
Subject: Definitions limit on label length in UTF-8
FWIW: I think that UTF-8 should NOT be a limit for Punycode. How an app (or
OS) encodes a decoded Punycode string internally is up to them. I doubt
we'd express such limits in GB-18030 or EUC-JP?
The only case I can think of for a UTF-8 limit is in the event someone made
a UTF-8 clean DNS in the future. However an ASCII punycode label is clearly
not the same thing, even if it represents a similar string.
In practice, all imposing a UTF-8 length limit does is to break IDNA2003
further, make it harder to code, and a little more error-prone.
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