Subject: Re: Semantic header (field) Content

From: John Stanley <[email-masked]>
Date: Thu, 7 Jul 2005 17:41:33 -0700 (PDT)

"Charles Lindsey" <chl@xxxxxxxxxxxxxxxx>:

>2. A followup agent is permitted (MAY) to prepend a "Re: " to the Subject
>if there is not one there already. Is it to be permitted to enclose that
>"Re: " within an encoded-word (I would hope not, because there is no
>benefit in doing so, and it is not done in current practice AFAIK). More
>to the point, however, is whether it is expected to decode an initial
>encoded-word before detecting whether an initial "Re: " is there already
>(I would not expect that to happen often - has anyone ever seen such a
>thing - but you never know).

It is quite proper for a user to enter the "Re: " by hand when modifying 
the Subject, and thus any agent that would normally encode the subject 
text will also encode the "Re: ". Unless it put the text there, it cannot 
tell whether that text is a "followup" marker or anything else. Even so, 
in most cases it will put the text there and then pass the Subject to the 
user, who can edit it, and thus the agent still cannot know if that string 
is a followup marker or not. 

So, logically, if "Re: " is to be used, it has to be detected in encoded 
Subjects. Otherwise you are stuck trying to demand that any agent that 
encodes a subject field body has to make special allowances for any 
potential "Re: " strings.

The same problem exists for your paragraph 1 with 'cmsg', except that 
'cmsg' is less likely to be inserted by hand (but there is still not zero 
chance).

---

From: John Stanley <[email-masked]>
Date: Fri, 8 Jul 2005 12:49:02 -0700 (PDT)

The "semantic content" (often abbreviated to just "content" when the
   context is clear) of a header field is its semantic interpretation;
   i.e. what remains after unfolding it and removing its field name with
   its colon and any leading and trailing whitespace and, in the case of
   structured headers only, ignoring comments and other semantically
   invisible items and replacing white space by a single SP.

This is fine, if you do not accept "Re: " or "cmsg" in the encoded part of 
a header field body as meaning ANYTHING special. In fact, it denies any 
special meaning to any encoded content of any field body, since decoding 
isn't part of your conversion from "field body" to "semantic content".