Definitions limit on label length in UTF-8
Shawn.Steele at microsoft.com
Mon Sep 14 18:59:08 CEST 2009
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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