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To: Dave Crocker <dcrocker@brandenburg.com>
Cc: drums@cs.utk.edu
Subject: Re: ABNF sets and sequences 
In-reply-to: <4.3.2.20000709223011.00bfebf0@mail.bayarea.net> 
References: <Your message of "Sun, 09 Jul 2000 11:58:24 +0900." <4.3.2.20000709114939.00b462f0@mail.bayarea.net> 
	<4.3.2.20000709223011.00bfebf0@mail.bayarea.net> 
Date: Sun, 09 Jul 2000 22:43:52 -0500
From: Philip Guenther <guenther@gac.edu>
List-Unsubscribe: <mailto:drums-request@cs.utk.edu?Subject=unsubscribe>

Dave Crocker <dcrocker@brandenburg.com> writes:
...
>Let's get specific about how the construct probably should be used:
>
>RFC 1894:
>
>>2.2 Per-Message DSN Fields
>>
>>    Some fields of a DSN apply to all of the delivery attempts described
>>    by that DSN.  These fields may appear at most once in any DSN.  These
>>    fields are used to correlate the DSN with the original message
>>    transaction and to provide additional information which may be useful
>>    to gateways.
>>
>>      per-message-fields =
>
>         SET (
>
>>           [ original-envelope-id-field CRLF ]
>>           reporting-mta-field CRLF
>>           [ dsn-gateway-field CRLF ]
>>           [ received-from-mta-field CRLF ]
>>           [ arrival-date-field CRLF ]
>>           *( extension-field CRLF )
>
>         )
>
>
>and in draft-ietf-drums-msg-fmt-07.txt:
>
>>name-val-list   =       [CFWS] [name-val-pair *(CFWS name-val-pair)]
>
>becomes
>
>>name-val-list   =       [CFWS]  SET [name-val-pair *(CFWS name-val-pair)]


That syntax makes no separation between the 'tag' that cannot be
repeated and what is being repeated.  That is, it would appear to ban
the following:

    To: joe.blow@some.where.com
    To: joe.blow@some.where.com

But not this:
    To: joe.blow@some.where.com
    To: jane.blow@some.where.com

Or even:
    To: joe.blow@some.where.com
    To:     joe.blow@some.where.com


Such an ABNF operator would have to explicitly specify what part of the
repeated content is required to be unique.  The uniqueness constraint
also has be made on the semantic value of the token, no?
    To: joe.blow@some.where.com
    tO: joe.blow@some.where.com


How about obsolete syntax:
    To: joe.blow@some.where.com
    To : joe.blow@some.where.com


Philip Guenther

----------------------------------------------------------------------
guenther@gac.edu		UNIX Systems and Network Administrator
Gustavus Adolphus College	St. Peter, MN 56082-1498
Source code never lies: it just misleads (Programming by Purloined Letter?)