Re: Use of LWSP in ABNF -- consensus call

Frank Ellermann <nobody@xyzzy.claranet.de> Fri, 18 May 2007 02:39 UTC

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From: Frank Ellermann <nobody@xyzzy.claranet.de>
Subject: Re: Use of LWSP in ABNF -- consensus call
Date: Fri, 18 May 2007 04:35:59 +0200
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John C Klensin wrote:

>     LWSP AtLeastOneRequiredThing CRLF
> or
>     [ LWSP optional-stuff ] CRLF

> I don't see either of the latter as problematic.

Depends on the protocol.  Your constructs match
      SP CRLF SP CRLF SP AtLeastOneRequiredThing CRLF
      SP CRLF SP CRLF SP optional-stuff CRLF
.........^^^^^^^^^^^^
If you do this e.g. in a mail or HHTP header, where
CRLF CRLF means "end of header", then any tool like
a text editor or other UA trying to reuse the header
field "as is" while silently removing trailing white
space would end up with
      CRLF CRLF SP AtLeastOneRequiredThing CRLF
      CRLF CRLF SP optional-stuff CRLF
......^^^^^^^^^

Frank