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Re: X-* header fields

2004-01-23 12:06:10

(one more response since this is back on the original topic of my

ned+ietf-822(_at_)mrochek(_dot_)com wrote:

The bottom line is that the success of x- fields in other places has 
from disasterous at worst to mixed at best. And to a large extent the lack 
harm in many spaces has come from lack of use. So if you're looking for 
for keeping the X- distinction from the successful use of X- in other 
I'm afraid it is not forthcoming.

For the record, I posed the question because there was a great deal of
discussion regarding X- header fields, but I can recall no recent discussion
about other use of x- for experimental and private use; as I mentioned, there
are many instances of such use in text messaging protocols (I was a little
surprised to see how many, and my list was not intended to be exhaustive -- I
simply listed the ones that I had implemented in one form or another). That
struck me as curious, hence my question about what was so unique to X- header
fields that caused so much discussion, whereas there was virtually no
discussion about other use of x- for similar purposes.  And if indeed use of 
in other places has been disastrous, why isn't there a call for its removal
from those places?

What makes you think there hasn't been such a call? The fact of the matter is
that X- media types have long been hanging by a thread. There most certainly
was a call to take them out at the time RFC 2048 came out, citing interop
problems. They remained only because the text was redone to discourage their
use and this was deemed to be sufficient. I was seriously tempted to remove
them in the recently approved RFC 2048bis but the mandate behind revision was
to make the minimal set of changes needed to open up the IETF tree to other
standards bodies, not to clean up other aspects of the specification. Even so,
there was some mumbling that retaining them wasn't a good idea. I certainly
would not bet the farm on their continued inclusion in any RFC 2048ter,
especially if the recent DNS tree proposal gains any traction.

There have been other, similar queries as to the wisdom of X- fields in other
contexts, but in most cases the lack of use of such fields is cited as a reason
not to change the status quo. The same cannot be said of X- headers, of course.


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