To the maintainers:
Help needed with a small grammar explanation.
At the moment I am interested in (at long last) making my exim.conf
somewhat aware of SPF/DKIM/DMARC in some regard, which has led me to
perusal of Chapter 58 of the exim 4.94 spec.
Coming from a world of Context-Free Grammars in general, and Backus_Naur
in particular, I frequently find myself bewildered by exim's---shall we
say---"interesting" configuration grammar. Nevertheless, I usually
manage after an exhaustive search of the latest version of the exim spec
to make sense of any constructs I come across in examples.
However, the DMARC example of 58.5 contains a construct that has me
totally stumped:
warn !domains = +screwed_up_dmarc_records
In an exhaustive search of the PDF version of the spec, I found exactly
98 occurrences of the symbol "!". Exactly one of those 98 instances (the
line quoted above) contains "!domains". None of the other 97 instances
appear to satisfactorily explain how to interpret the construct in
question.
Presumably the left side of the "=" is negated in some manner, but that
is about as much as I think I understand. The right side looks
sufficiently close (linguistically speaking) to "foobar" that I think I
have some glimmer of understanding of that. But, maybe not.
A pointer to the specific section of the spec that explains the concept
I am missing would be sufficient.
Phil
