IDNA and U+08A1 and related cases (was: Re: Barry Leiba's Discuss on draft-ietf-json-i-json-05: (with DISCUSS and COMMENT))
Shawn.Steele at microsoft.com
Tue Jan 27 02:08:43 CET 2015
> I'd say that the fundamental design limitation of DNS (never mind IDNA) in this
> context is that a domainname's labels are supposed to make good identifiers
> (observe: hand-waving about what an "identifier" is).
I think this is a big part of the problem. In some contexts an identifier has to have a 1:1 mapping with an idea and round trip. So if I have a "thing", then I can figure out what its one (and only) identifier is.
In other cases though, we want identifiers to be a little fuzzy. It's convenient that DNS maps upper & lower case ASCII (unless you're Turkish) for example. Software often lowercases them so it ends up with it's 1:1 mapping. So you end up with an n:1 system that will probably spit out a 1:1 label after it's been processed. It worked mostly because the casing rules were consistent and used everywhere.
Not exactly a confusable, but I'd've mapped ALL 4 of the Latin I forms together. Then there's no confusion about which identifier is used for a label but it wouldn't always round-trip to a "pretty" label. Some have made an argument that DNS doesn't have to be pretty though, and if people wanted to advertise the pretty form it'd still resolve to the same thing.
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