Re: Use of LWSP in ABNF -- consensus call

Dave Crocker <> Sat, 22 September 2007 16:43 UTC

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Date: Sat, 22 Sep 2007 09:42:25 -0700
From: Dave Crocker <>
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Subject: Re: Use of LWSP in ABNF -- consensus call
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On 5/14/2007 Lisa Dusseault wrote:

> The IESG reviewed 
> <> 
> for publication as Internet Standard and would like to know if there is 
> consensus to recommend against the use of LWSP in future specifications, 
> as it has caused problems recently in DKIM and could cause problems in 
> other places.
> Some discussion on this point already:
>  -
>  -
>  -
>  - 
> (in this tracker comment, Chris Newman recommended to remove LWSP, but 
> for backward-compatibility it's probably better to keep it and recommend 
> against use)


The current situation with elevating the ABNF document to full Internet 
Standard is that Lisa has a Discuss hold on it, on behalf of an IESG view that 
a warning note should be attached.

Acting as an individual contributor, Chris Newman has offered the following 
change to the document, as a possible means of resolving things:

> OLD:
>         LWSP           =  *(WSP / CRLF WSP)
>                        ; linear white space (past newline)
> NEW:
>         LWSP           =  *(WSP / CRLF WSP)
>                        ; Use of this linear-white-space rule permits
>                        ; lines containing only white space that are no
>                        ; longer legal in mail headers and have caused
>                        ; interoperability problems in other contexts.
>                        ; Do not use when defining mail headers and use
>                        ; with caution in other contexts.

The nature of the IETF process is such that there are no guarantees for what 
will resolve a Discuss, but the signs are good that a consensus on this list, 
for a note of this type, will suffice.

The premise is that the discussion on this list, last May, had consensus to 
retain the LWSP construct and consensus to add a warning.  The text that Chris 
is suggesting seems to accomplish this.

In spite of saying "Do not use", the comment is non-normative, in formal IETF 
specification terms.  Yet it does seem to adequately describe the problem and 
the way to deal with it.

           So, I'm going to ask for a consensus call on this
           modification, where the assumption is that the text
           is acceptable.

           All that is needed is for folk who *object* to speak up
           and state their reasons.

           If there is consensus *against* this change, we'll have to
           try something else.

           Absent a consensus *against* the wording change, we will
           propose it to Lisa and see if that resolves her Discuss.

           This consensus call closes on Sunday, 30 September.



   Dave Crocker
   Brandenburg InternetWorking