Comma-seperated lists

On 2008-01-26, Frank Ellermann wrote:
> 
> Pete Resnick wrote:
> 
>  [# and LWSP] 
> > What? What does one thing have to do with the other?
> 
> ,,,,,   ,,,,,    ,,,,    ,,,,,
>   ,     ,       ,          ,
>   ,     ,,,,     ,,,       ,
>   ,     ,           ,      ,
>   ,     ,,,,,   ,,,,       ,   
> 
> | The full form is "<n>#<m>element " indicating at least
> | <n> and at most <m> elements, each separated by one or
> | more commas (",") and optional linear whitespace (LWS).
>  [RFC 2068 2.1, similar in 2069, 2616, 2617, 2831]  ^^^
> 
> With optional FWS you get ASCII art.  With LWS you would
> get "apparently empty lines"

No, you get a list with empty elements (N.B. not allowed for message
generation for any lists in RFC 2822 or draft-resnick-2822upd-04.txt).

> - causing havoc if something  
> in transit manages to transform them into a "really empty
> line" (indicating the end of the header, CRLF CRLF).

Quoting draft-klensin-rfc2821bis-06.txt:
"
   As discussed in Section 6.4, a relay SMTP has no need to inspect or
   act upon the header section or body of the message data and MUST NOT
   do so except to add its own "Received:" header field (Section 4.4)
   and, optionally, to attempt to detect looping in the mail system (see
   Section 6.3).  Of course this prohibition also applies to any
   modifications of these header fields or text (see also Section 7.9).
"

Your hypothetical "something" is nonconforming and non-interoperable.