diff --git a/doc/src/sgml/ref/pgarchivecleanup.sgml b/doc/src/sgml/ref/pgarchivecleanup.sgml
index 60a7fc4..c375a88 100644
--- a/doc/src/sgml/ref/pgarchivecleanup.sgml
+++ b/doc/src/sgml/ref/pgarchivecleanup.sgml
@@ -80,6 +80,10 @@ pg_archivecleanup:  removing file "archive/00000001000000370000000E"
    <replaceable>archivelocation</> is a directory readable and writable by the
    server-owning user.
   </para>
+  <para>
+   WAL file segments (including partial ones) are deleted, while timeline
+   history files and backup history files are not.
+  </para>
  </refsect1>
 
  <refsect1>