2. d= is sufficient for ADSP's stated goal.
3. The current ADSP re-defines i= semantics. While this is theoretically
legal, it is neither necessary nor useful. So the important question is not
about legality, but about need. ADSP's use of i= makes the meaning of DKIM
constructs more complicated and contingent. As a specific example, why should
ADSP use require Levine to alter his signing practices, given that they are
entirely legal with respect to DKIM signing?
I'll note that Jim posted a draft:
to float the concept that this sort of thing can be done with another
tag that doesn't try to overload the meaning of an existing one. I'll
note that the same sort of thing can be used if we want to narrow the
scope of ADSP tighter than just the domain.
I'll also note that such a thing could be done in the base ADSP... or
in an extension to ADSP that's written later.
I'm not sure what my opinion is on that last point, but on the first
point I think it's best to define an identifier that's specifically
for ADSP's use, if we want that function. Some signers may give that
tag the same value they give i=, and there's no harm done. Some
signers may use a different value, which would demonstrate the wisdom
of separating them.
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