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Proposal for i111 / i63

From: Mark Nottingham <mnot@mnot.net>
Date: Fri, 4 Apr 2008 12:29:16 +1100
Message-Id: <42C36CAE-F708-4846-A3BE-ABE6E031A102@mnot.net>
To: HTTP Working Group <ietf-http-wg@w3.org>

This is the parts of my revised proposal for i74 that are specific to  
i111 and i63. I've mostly used HTTP-style BNF, not ABNF, for purposes  
of comparison.

* p1, 2.2:
Old:
>  The TEXT rule is only used for descriptive field contents and values
>  that are not intended to be interpreted by the message parser.  Words
>  of *TEXT MAY contain characters from character sets other than ISO-
>  8859-1 [ISO-8859-1] only when encoded according to the rules of
>  [RFC2047].
>    TEXT           = %x20-7E | %x80-FF | LWS
>                   ; any OCTET except CTLs, but including LWS
>  A CRLF is allowed in the definition of TEXT only as part of a header
>  field continuation.  It is expected that the folding LWS will be
>  replaced with a single SP before interpretation of the TEXT value.

New:
"""
Words of *TEXT MUST NOT contain characters from character sets other  
than ISO-8859-1 [ISO-8859-1].

    TEXT           = %x20-7E | %x80-FF | LWS
                   ; any OCTET except CTLs, but including LWS

A CRLF is allowed in the definition of TEXT only as part of a header  
field continuation.  It is expected that the folding LWS will be  
replaced with a single SP before interpretation of the TEXT value.

Characters outside of ISO8859-1 MAY be included where the encoded-word  
rule (as defined in RFC2047, Section 2) is specified. The encoded-word  
rule is only used for descriptive field contents and values that are  
not intended to be interpreted by the message parser. When used in  
HTTP, encoded-word has no specified length limit.
"""

Note that I've taken a minimal approach to #63 here, and that the  
outcome of i74 may change this.


* p1, 2.2:
Old:
> comment = "(" *( ctext | quoted-pair | comment ) ")"

New:
"""
comment = "(" *( ctext | quoted-pair | comment | encoded-word ) ")"
"""


* p1, 4.2:
Old:
>    field-content  = <field content>
>                     ; the OCTETs making up the field-value
>                     ; and consisting of either *TEXT or combinations
>                     ; of token, separators, and quoted-string

New:
"""
field-content = <field content>
  ; the OCTETs making up the field-value,
  ; according to the syntax specified by the field.
"""

N.B. depending on how we resolve i74, we may want to add a constraint  
regarding character encodings, so that people don't start minting  
headers in random ones.


* p3, B.1:
Old:
> filename-parm = "filename" "=" quoted-string

New:
"""
filename-parm = "filename" "=" quoted-string | encoded-word
"""

N.B.


* p6, 16.6:
Old:
> warn-text = quoted-string
New:
"""
warn-text = quoted-string | encoded-word
"""


Note that I have NOT suggested the use of encoded-word in the  
following places:

p1, 3.4 (Transfer Codings -- parameter values), p1, 6.1.1 (Reason- 
Phrase), p2, 10.2 (expect-extensions), p3, 3.3 (Media Types --  
parameter values), p3, 6.1 (accept-extension), p4, 3 (ETag opaque- 
tag), p6, 16.2 (cache-extension), p6, 16.4 (extension-pragma).

I think the *-extension and parameter value ones are straightforward;  
if a particular extension wants to specify use of encoded-word, it  
should; we shouldn't specify use of encoded-word in the generic  
extension construct, but leave it to the specific instances. I.e.,  
they still conform to TEXT, it's up to them to specify if that content  
can contain encoded-words.


--
Mark Nottingham     http://www.mnot.net/
Received on Friday, 4 April 2008 01:29:53 GMT

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