[Email-SIG] header folding

[R. David Murray]

On Tue, 26 Jul 2011 13:03:11 +0900, "Stephen J. Turnbull" <stephen at xemacs.org> wrote:
> R. David Murray writes:
> 
>  > the end.  Basically, BaseHeader gets a 'wrap' method, and there is
>  > a new policy control, 'refold_source' (I'll probably rename it to
>  > 'rewrap_source', since I expect to apply it also to message
>  > bodies).
> 
> This bothers me.  Folding and wrapping are two different things.
> 
> Folding is about invertibly reformatting a single logical line to make
> machines happy during transmission, what wrapping "does" is not 100%
> clear to me but it's about making people happy.  (I put "does" in
> quotes because it's not obvious to me that the source of wrapped text
> necessarily is a single anything, nor that wrapping need be
> invertible.)
> 
> I grant that people and many MUAs take a different point of view about
> header folding, but clearly the RFCs have moved away from placing any
> importance on presentation aspects toward specifying an invertible
> transformation exactly.  On the other hand, I think that wrapping
> should place emphasis on presentation.

Hmm.  Makes sense to me.  So you'd rather the method were called "fold"
and that refold_source remains the name of the policy control.

What's the word for what is done when a text message is made to have
a line length of less than 78 by using quoted printable (or base64)
encoding?  Is that also folding?  If there's no existing term in common
use, folding would make sense to me.  So I have no objection to using
'fold' consistently in the api and code for these operations.

Can anyone see a use case for controlling folding of headers separately
from folding of message bodies?  I haven't thought of one, which is why
I'm thinking one policy knob controls both.

--David