-If specified, L<public-inbox-watch(1)> will only process mail matching
-the given header. If specified multiple times, mail will be processed
-if it matches any of the values.
+If specified, L<public-inbox-watch(1)> will only process mail
+matching the given header. If specified multiple times in
+public-inbox 1.5 or later, mail will be processed if it matches
+any of the values. Only the last value was used in public-inbox
+1.4 and earlier.