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Re: X-* header fields

2004-01-07 05:12:38

In <3FFA6ED6(_dot_)9030906(_at_)verizon(_dot_)net> Bruce Lilly 
<blilly(_at_)verizon(_dot_)net> writes:

Here's another take on the subject (I hope it doesn't open up several cans
of worms, but here goes...)

X- is used as an indicator for experimental or private-use tags in many 
in Internet message protocols other than field names. For example:

charsets (RFC 2978, sect. 3.1, also RFC 2046, sect. 4.1.2)
MIME media types (RFC 2045, sections 5 & 5.1, also RFC 2046, section 6) 
and subtypes
language tags (RFC 3066, section 2.2)
disposition-notification options (RFC2298 section 2.2 )
transfer encodings (RFC 2045, sect. 6.3)
MTA-name-types (RFC 3464 sect. 2.2)
access-types (RFC 2046 sect
address-types (RFC 2298 sect. 3.1.2, also RFC 3464 sect. 2.2)
dispositions (RFC 2183 sect 2.8)
diagnostic types (RFC 3464 sect. 2.2)
disposition modifiers (RFC 2298 sect

And generally speaking for tokens to introduce new parameters in
Content-Type and other headers that use the same parameter syntax.

And also in NNTP where there are widely deployed commands such as XOVER
and XHDR. Nevertheless, the new NNTP draft if defining new commands OVER
and HDR even though their syntax/semantics is 99.9% identical.

And is mentioned in Keith's auto-response draft for auto-submitted types 
-- and I don't recall
any discussion about that here when that draft was recently discussed.

And of course there are MDN X- fields (RFC 2298 sect. 3.3) and DSN X- 
fields (RFC 3464
sect. 2.4).

So what's so abhorrent about top-level X- fields (RFC 822) that doesn't 
also apply to
charsets, media types, language tags, etc.?

I agree. There is a widespread understanding that these X-things don't get
standardized as such.

Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 Fax: +44 161 436 6133   Web:
Email: chl(_at_)clerew(_dot_)man(_dot_)ac(_dot_)uk      Snail: 5 Clerewood Ave, 
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