X-headers are very useful for experimental features and private agreements -
in fact, x-headers have been quite a problem. they are excellent in
theory, but the header can become popular, thereby becoming a de facto
standard. then we are stuck with a defacto standard that uses and x- label.
the view that we simply re-label the header with a non-x value does not
match the last 20 years of history.
simply registering headers does not encourage or discourage private or
public efforts.
instead it does exactly what it is supposed to do, namely make sure that we
have a coherent, public name space and accountability for who is consuming
it -- that is, where to go to find out about a particular header.
d/
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Dave Crocker <mailto:dcrocker(_at_)brandenburg(_dot_)com>
Brandenburg InternetWorking <http://www.brandenburg.com>
tel +1.408.246.8253; fax +1.408.273.6464