Re: [dmarc-ietf] Errors in RFC 8601, was Question about changes introduced by erratum

John R Levine <johnl@taugh.com> Sun, 22 March 2020 21:13 UTC

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Date: Sun, 22 Mar 2020 17:13:28 -0400
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From: John R Levine <johnl@taugh.com>
To: Damian Lukowski <rfc@arcsin.de>, dmarc@ietf.org
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Subject: Re: [dmarc-ietf] Errors in RFC 8601, was Question about changes introduced by erratum
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>> No, see RFC 2821 or 5321 sec 3.3.  The reverse-path is what's between
>> the brackets, which means it's a mailbox or it's empty.
>
> Ok, I guess I didn't expect to have to go through a layer of english
> while assembling a grammar from different sources, given that there was
> an ABNF rule with a matching name.

Figuring out the actual syntax of A-R is quite hard because there are so 
very many external references.

Even the ABNF is tricky -- I had to stare at the definitions of resinfo 
and propspec and pvalue for quite a while to confirm that your 
interpretation was correct.

A lot of people (not you) when reading RFC 5234 assume that there has to 
be only one way that the BNF can match a string.  That's not true, 
ambiguous matches are allowed, and sometimes can make the ABNF simpler.

Regards,
John Levine, johnl@taugh.com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly