Re: [ietf-822] "--" first in lines to indicate start of signature

[Hector Santos <[e-mail]>]

On 1/4/2016 8:39 AM, Jacob Palme wrote:
>
> On 3 jan 2016, at 00.05, Murray S. Kucherawy wrote:
>
>> What other uses of "--" on a line by itself are there?  The only thing I can think of is ASCII art.
>
> I have used "--" to separate sections in a longer plain text document. I have learned to not use it in that way in mail messages, and use "==" instead of "--". But it is a simple mistake to make if you are not aware of its special meaning in mail messages. Which probably many mail users are, everyone is not an expert on mail protocols, as we who subscribe to this mailinglist are.
>

Jacob, since the 80s, I've written a number mail reader/writers, 
a.k.a. MUAs, mail tossers, importers/exporters, gateways/mailers, etc 
for several networks and mail formats where each had its own technical 
relationship to body parts such as "tear lines" and "Origin" lines, 
and/or kludge lines.

For the old school Fidonet mail network, the Fidonet Technical 
Standards provided early guidelines.


http://ftsc.org/docs/
http://ftsc.org/docs/fsc-0043.002
http://ftsc.org/docs/fsc-0046.005

(I was looking for a specific one that also described the tear line 
with line information, I couldn't find it offhand.)

Many IETF folks has a history with Fidonet.   I recall FSC-0046 was 
JoHo's attempt to add "commercial tagging" using a PID (Product ID) 
kludge line because of the Tear Line and Tag line "Stripping Wars." 
The proposal tried to give some guidelines for mail product developers 
to follow at the time.  I recall the "Stripping Wars" when some 
product vendors began to add/strip/replace the tear line with "--- Not 
Registered" tags and other mail products and even operators stripped 
and replaced it with there own tags during the transport process.   In 
fact, to illustrate the problem, I added logic in a MUA to completely 
hide them and/or replace it with a "visual" change, not a physical 
mail storage change. Call it Visual Tampering!  It goes to show how 
young MUA technology is still is because it is ultimately the tool 
that people use to SEE the mail with.

Also, there are other "formats" for this, three dashes "---" and 
"Origin Line" style " * " that FSC-0043 describes.   Add the QWK tag 
line, its possible to see 2-4 lines:

--  User Line, maybe.
--- Mail Product Line
  *  Original Domain line

Look at the line that the iPhone and iPad adds to each message 
automatically.  There is no rule that says it has to remain there. :)

At the end of the day, we don't have control over the body nor what 
the MUAs wants the user to see.  But I agree, the Mail Creator, the 
MUA, should probably have some RFC5322 related guideline on what to 
use.  When the move was made to RFC 822/2822 several decades ago,  I 
wasn't aware of any "IETF guideline" for this.  There is probably some 
I-D or RFC proposal now or someone can come up with one but overall, 
if it begins to get exploited with overhead text, commercialization 
concepts, etc, its going to get stripped and "visually" hidden.  :) 
Just consider that new mail viewing devices doesn't have the real 
estate for such overhead.

-- 
HLS