favor git(1) rather than libgit2 for ExtSearch

[public-inbox.git] / Documentation / public-inbox-glossary.pod

diff --git a/Documentation/public-inbox-glossary.pod b/Documentation/public-inbox-glossary.pod
index 61e1e9f8b1f777422ed8160779d3def9c67c2445..f17f2d28709a0641b39c7a14d25b5e546dcc02a6 100644 (file)
--- a/Documentation/public-inbox-glossary.pod
+++ b/Documentation/public-inbox-glossary.pod
@@ -15,6 +15,8 @@ tools.
 
 =head1 TERMS
 
+=over 8
+
 =item IMAP UID, NNTP article number, on-disk Xapian docid
 
 A sequentially-assigned positive integer.  These integers are per-inbox,
@@ -69,8 +71,8 @@ L<public-inbox-nntpd(1)> or L<public-inbox-imapd(1)>
 
 Private, per-message keywords or flags as described in RFC 8621
 section 10.4.  These are conveyed in the C<Status:> and
-C<X-Status:> headers for L<mbox(5)>, as IMAP FLAGS (RFC 3501 section 2.3.2),
-or Maildir info flags.
+C<X-Status:> headers for L<mbox(5)>, as system IMAP FLAGS
+(RFC 3501 section 2.3.2), or Maildir info flags.
 
 L<public-inbox-watch(1)> ignores drafts and trashed (deleted)
 messages.  L<lei-import(1)> ignores trashed (deleted) messages,
@@ -83,6 +85,15 @@ the same email into one or more virtual folders for
 ease-of-filtering.  This is NOT tied to public-inbox names, as
 messages stored by lei may not be public.
 
+These are similar in spirit to arbitrary freeform "tags"
+in mail software such as L<notmuch(1)> and non-system IMAP FLAGS.
+
+=item volatile metadata (VMD)
+
+For L<lei(1)> users only, this refers to the combination of
+keywords and labels which are subject to frequent change
+independently of immutable message content.
+
 =item IMAP INTERNALDATE, JMAP receivedAt, rt: search prefix
 
 The first valid timestamp value of Received: headers (top first).
@@ -97,6 +108,8 @@ If no Date: header exists, the time from the Received: header is
 used, and then the current time if neither header exists.
 When mirroring via git, this is the git author time.
 
+=back
+
 =head1 COPYRIGHT
 
 Copyright 2021 all contributors L<mailto:meta@public-inbox.org>