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

["Eric A. Hall" <ehall@ehsco.com>]

Adam M. Costello wrote:

 >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?  :)

You are the only one that is unclear on it. 0x80-0xFF must match
exactly. Any usage of any of these character codes is allowed and legal,
but the meaning of those codes only has context within the application
that uses the data. As far as STD13 is concerned, these aren't
necessarily even characters, they are just eight-bit codes.