[idn] Suggested clarifications of the IDN requirements document

[Harald Tveit Alvestrand <alvestrand@cisco.com>]

Apologies for not having sent these before.

I suggest the following changes to the IDN requirements document, version -03:

[2.5] The DNS service layer (the packet formats that go on the wire)
MUST NOT limit the codepoints that can be used. This interface SHOULD
NOT assign meaning to name strings; the application service layer,
where "gethostbyname" et al reside, MAY constrain the name strings to
be used in certain services. (conflict)

Change to

[2.5] The DNS protocol (the packet formats that go on the wire) MUST NOT
limit the codepoints that can be used.
A service defined on top of the DNS, for instance the IDN-to-Address function,
MAY limit the codepoints that can be used.
The service description MUST describe what limitations are imposed.

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[4] The protocol SHOULD allow creation of caching servers that do
not understand the charset in which a request or response is encoded.
The caching server SHOULD perform correctly for IDN as well as for
current domain names (without the authoritative bit) as the master
server would have if presented with the same request.

Change to

[4] The protocol MUST NOT require that current cache servers be modified
to support IDN. If a cache server can have additional functionality to
support IDN better, this additional functionality MUST NOT cause problems
for resolving current domain names.

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[18] The protocol SHOULD NOT place any restrictions on the
application service layer. It SHOULD only specify changes in the DNS
service layer and within the DNS itself.

Suggest to delete this requirement.
-------------
[37] The protocol MUST work for all features of DNS, IPv4, and IPv6.

Change to:

[37] The protocol MUST support the following operations:
- Mapping an IDN to IPv4 addresses
- Mapping an IDN to IPv6 addresses
- Mapping an IDN to an MX record
The protocol SHOULD support the following operations:
- Mapping an IPv4 address to an IDN
- Mapping an IPv6 address to an IDN
The protocol MAY support other operations.
The protocol MUST NOT allow an IDN to be returned to a requester
that requests the IP-to-(old)-domain-name mapping service.

I suggest also that this requirement be moved to be [2.6] - I think it is 
critical for knowing what solutions can be allowed, and should be early in 
the document.

NOTE: I am trying to make sure we know what we want here.
Discussion encouraged!


--
Harald Tveit Alvestrand, alvestrand@cisco.com
+47 41 44 29 94
Personal email: Harald@Alvestrand.no