[Ltru] status of RFC 3066 or RFC 3066bis in relation to HTTP Accept-Language

Mark Crispin mrc at CAC.Washington.EDU
Fri Mar 24 18:11:58 CET 2006

As a long-time IETFer:

Typically, these matters are handled on an ad-hoc case-by-case basis in 
which common sense prevails.

The razor in this case is "does something break?"  Most updates to IETF 
documents expand upon, or clarify, what was in the older document; they do 
not introduce an incompatibility.  If something is removed, that is 
generally because there is community concensus that it is bad juju.

So, given RFC abcd that normatively references RFC efgh that has been 
obsoleted by RFC ijkl:
  . can two RFC abcd implementations communicate with each other, and the
    desired behavior happen, even though one uses RFC efgh and the other
    uses RFC ijkl?

If the answer is yes, then the question is effectively academic in nature. 
Sometime in the future, RFC abcd will have to be updated to reflect the 
change to RFC ijkl, but as it doesn't break interoperability it isn't 
urgent.  One might expect that old implementations will use RFC efgh and 
new implementations will use RFC ijkl.

If the answer is no, then someone was not doing their job; RFC ijkl should 
not have been approved without that working group taking on the needed 
update to RFC abcd.  An important purpose of the IETF/IESG bureaucracy is 
to prevent something like this from happening.

Hence the answer that since RFC abcd normatively refers to RFC efgh, it is 
RFC efgh that is used by an RFC abcd implementator.  It is, however, 
expected that people would tend to use RFC ijkl instead (if only because 
it has clearer wording and represents more modern understanding) -- and 
sooner or later, RFC abcd will be obsoleted by a RFC mnop that makes this 
change official.

Equally important is that RFC ijkl should not have been approved for 
publication if it creates an incompatibility problem in RFC abcd, without 
also updating/obsoleting RFC abcd.

-- Mark --

Democracy is two wolves and a sheep deciding what to eat for lunch.
Liberty is a well-armed sheep contesting the vote.

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