Consensus Call Tranche 7 (BiDi Model)

Andrew Sullivan ajs at commandprompt.com
Wed Oct 15 17:38:03 CEST 2008


On Wed, Oct 15, 2008 at 04:29:38PM +0200, Harald Alvestrand wrote:

> how else can we formulate "don't do this"?

First, I am not convinced, even a little bit, that the specification
ought to be saying any MUSTs about contents of zone files.  But what
about this:

    Zone operators SHOULD have a policy that forbids accepting as 
    U-labels strings that fail the BIDI criterion.  Zone operators
    SHOULD NOT generate A-labels from a putative U-label that fails
    the BIDI criterion, and SHOULD NOT insert such A-labels in zone
    data.  

Alternatively,

    Zone operators conforming to this specification MUST have a policy
    that forbids accepting as U-labels strings that fail the BIDI
    criterion.  Zone operators conforming to this specification MUST
    NOT generate A-labels from a Putative U-label that fails the BIDI 
    criterion, and MUST NOT insert such A-labels in zone data.

if you really want to use the MUST. In my opinion, the second form is
actually weaker, since the first imposes an implied restriction on
zone operations (which is not a matter for DNSEXT, I'm delighted to
say, althought DNSOP might have something to say about it) whereas the
second only imposes a restriction on those claiming to conform to the
specification.  
 
> But I want to think that this is implicit in "conformance to IETF 
> protocols is voluntary" and "IDNA2008 is a different specification from 
> the DNS". Otherwise, modularization suffers.

I agree, which is why I'm picking at this nit.

A

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Andrew Sullivan
ajs at commandprompt.com
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http://www.commandprompt.com/


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