In <4023162E(_dot_)7060003(_at_)verizon(_dot_)net> Bruce Lilly
<blilly(_at_)verizon(_dot_)net> writes:
Bruce Lilly wrote:
obs-text only appears in text (where obs-char makes more sense) and
obs-utext (which is defined as obs-text). obs-utext appears only in utext,
and utext appears only in unstructured.
I'll take another look at the unstructured and related productions.
OK, here's another attempt. Working backwards from unstructured fields:
comments = "Comments" ":" unstructured CRLF
obs-comments = "Comments" *WSP ":" [FWS] obs-unstructured CRLF
etc.
N.B. no [FWS] after the colon in the non-obs fields (an unstructured
field cannot be allowed to end with FWS (which it would do if the
"unstructured" production is empty) using non-obs rules, since that
would leave CRLF 1*WS CRLF, i.e. a whitespace only "continuation"
line at the end of the field, which is prohibited by sect. 3.2.3.).
Per contra, that must be permitted in the obs- unstructured fields.
That is why separate unstructured and obs-unstructured productions
are required.
No, that does not work, because you have just forbidden a header made up
exactly as follows:
"Comments" ":" SP CRLF
That is currently permitted by RFC 2822 (even for generating), and is
indeed what I would expect most MUAs to generate (assuming they did not
omit the header altogether).
Preventing folded headers with only WSP in a line through the syntax would
be so horrendously complex that it should not be attempted. Which is why
it is currently done by verbiage in 3.2.3. So I think the best you can do
is to allow [FWS] in that header, and leave the wording in 3.2.3 to cover
the situation.
Having said that, the wording in 3.2.3 could be tightened up. Currently,
it applies to CFWS only (and not to FWS, so you could seemingly have a
Date header folded over many empty lines).
--
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