OK, though it really ought be used only to help find messages that
might be part of the thread, not to define it.
I don't think anyone uses it as the complete, ultimate list of messages
in that thread. I suspect most programs that utilitze it only care
about the immediate parent message.
References should be like that section at the end of a paper in a conference
or journal, where you list the identities of all the earlier papers that your
paper refers to (substituting message for paper.) That cannot simply be all
of the References from each earlier paper (message) with a reference to the
most recent one tacked on...
Well, how they SHOULD be used, I can't really say. I can only go by the
standards documents.
Using the References header is just fine - just don't start making assumptions
about what it will (or should) contain that conflict with how the header
should really be being used.
Well ....
It looks like References came from Usenet/Netnews; it's mentioned in
RFC 1036. That RFC basically says, "To construct the References header,
tack on the parent message-id to the existing References header. You're
allowed to truncate it, but keep as many entries as possible".
RFC 5536 (whoah, someone updated those RFCs in 2009? I didn't think people
were still using Usenet then!) basically says, "See RFC 5322".
RFC 5322 says, §3.6.4:
The "References:" field will contain the contents of the parent's
"References:" field (if any) followed by the contents of the parent's
"Message-ID:" field (if any). If the parent message does not contain
a "References:" field but does have an "In-Reply-To:" field
containing a single message identifier, then the "References:" field
will contain the contents of the parent's "In-Reply-To:" field
followed by the contents of the parent's "Message-ID:" field (if
any). If the parent has none of the "References:", "In-Reply-To:",
or "Message-ID:" fields, then the new message will have no
"References:" field.
Note: Some implementations parse the "References:" field to
display the "thread of the discussion". These implementations
assume that each new message is a reply to a single parent and
hence that they can walk backwards through the "References:" field
to find the parent of each message listed there. Therefore,
trying to form a "References:" field for a reply that has multiple
parents is discouraged; how to do so is not defined in this
document.
_If_ MUAs are following the standards, then a References header should
contain a complete list of parent messages back to the origin message.
I suspect that all threading programs care about is the immediate parent,
though. I recall Ralph had some reason he used References instead of
In-Reply-To, but I don't remember what it was.
--Ken
_______________________________________________
Nmh-workers mailing list
Nmh-workers(_at_)nongnu(_dot_)org
https://lists.nongnu.org/mailman/listinfo/nmh-workers