1 files changed, 7 insertions, 1 deletions
diff --git a/lib/PublicInbox/Msgmap.pm b/lib/PublicInbox/Msgmap.pm
index 6e9f2743..8fe17a95 100644
--- a/lib/PublicInbox/Msgmap.pm
+++ b/lib/PublicInbox/Msgmap.pm
@@ -1,6 +1,12 @@
  # Copyright (C) 2015 all contributors <meta@public-inbox.org>
  # License: AGPLv3 or later (https://www.gnu.org/licenses/agpl-3.0.txt)
-# bidirectional Message-ID <-> Article Number mapping
+
+# bidirectional Message-ID <-> Article Number mapping for the NNTP
+# and web interfaces.  This is required for implementing stable article
+# numbers for NNTP and allows prefix lookups for partial Message-IDs
+# in case URLs get truncated from copy-n-paste errors by users.
+#
+# This is maintained by ::SearchIdx
  package PublicInbox::Msgmap;
  use strict;
  use warnings;