Re: [idn] WG last call summary

["Adam M. Costello" <idn.amc+0@nicemice.net.RemoveThisWord>]

"Eric A. Hall" <ehall@ehsco.com> wrote:

> domain names which are used by applications, protocol messages and
> data-formats MUST be passed and displayed in LDH form, except where
> the governing specification has explicitly defined an IDN behavior for
> the affected domain name, and that the use of ToUnicode is expressly
> prohibited if the governing specification has not defined how and
> where that function will be deployed.

Let me make sure I'm understanding you correctly.  For a given domain
name slot (protocol element, structured data field, function argument,
etc), the governing specification says what you may write into that
slot, and tells how to interpret what you read out of that slot, but it
does not dictate what you may do with the name after you've read it.
That depends on what you're going to do with the name next.

For example, if an application reads a name from slot X and writes it to
slot Y, then it's the specification of slot Y that determines whether
ToUnicode can be performed along the way, not the specification of slot
X.  If the application reads a name from slot X and displays it, then
it's the specification of the application itself that determines whether
ToUnicode can be performed.

Do we agree on all that?

If so, then your paragraph quoted above is stipulating the same
requirement as rule 1 of IDNA: domain labels written into domain name
slots MUST be in ASCII form unless the specification of the slot
explicitly provides for non-ASCII labels.

> Structured data-types that incorporate domain names as key elements
> (such as URLs and email addresses) MUST be processed according to
> the rules which govern those data formats.  Applications MUST NOT
> perform ToUnicode conversions against structured data-types unless
> this conversion has been explicitly prescribed by the governing
> specifications.

This is another form of rule 1 of IDNA.

> Generally speaking, it is RECOMMENDED that applications allow users
> to enter or view domain names in their preferred encoding formats
> wherever this is allowed...

This looks an awful lot like rule 2 of IDNA.  SHOULD and RECOMMENDED are
equivalent according to RFC 2119.

From the IDNA draft:

    1) Whenever a domain name is put into a generic domain name slot, every
    label MUST contain only ASCII characters.

    2) ACE labels obtained from domain name slots SHOULD be hidden from
    users except when the use of the non-ASCII form would cause problems
    or when the ACE form is explicitly requested.  When requirements 1
    and 2 both apply, requirement 1 takes precedence.

Isn't this very close to what you're saying?

("Generic domain name slot" is defined earlier in the draft, and
includes any structured-data domain name whose specification does not
explicitly provide for IDNs.)

IDNA does not explicitly say something like "when using protocols, data
formats, and interfaces, you MUST follows the rules governing them", but
that goes without saying.

AMC