Re: [idn] I-D ACTION:draft-ietf-idn-idna-08.txt

[Mark.Andrews@isc.org]

> Mark.Andrews@isc.org wrote:
> 
> >       I don't know what's "unclear" or "silent" about the following
> >       from RFC 1035.
> >
> > Although labels can contain any 8 bit values in octets that make up
> > a label, it is strongly recommended that labels follow the preferred
> > syntax described elsewhere in this memo, which is compatible with
> > existing host naming conventions.  Name servers and resolvers must
> > compare labels in a case-insensitive manner (i.e., A=a), assuming
> > ASCII with zero parity.  Non-alphabetic codes must match exactly.
> 
> How do I "compare labels assuming ASCII with zero parity" when the input
> strings are not ASCII or don't have zero parity?  If I can really assume
> zero parity, then I can ignore the 8th bit completely and compare only
> the bottom 7 bits.  On the other hand, "match exactly" suggests that I
> should require the 8th bit to match too.  But even then, among the codes
> 128..255, which are non-alphabetic?  I don't know, but I'm required to
> do a case-insensitive comparison, so I'm screwed.
> 
> Is that unclear enough for you?  :)
> 
> AMC

	The alphabetic characters in this context are 0x41-0x5a and 0x61-0x7a
	(zero parity ASCII A-Z, a-z).  All others are compared exactly.

	Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews@isc.org