diff --git a/pmg-mail-filter.adoc b/pmg-mail-filter.adoc
index c927d1c..92127c6 100644
--- a/pmg-mail-filter.adoc
+++ b/pmg-mail-filter.adoc
@@ -186,4 +186,15 @@ Test if the mail address belong to a specific LDAP user or group.
 
 We have two important WHO objects called 'Blacklist' and
 'Whitelist'. Those are used in the default ruleset to globally block
-or allow specific senders.
\ No newline at end of file
+or allow specific senders.
+
+WHEN - objects
+--------------
+
+image::images/screenshot/pmg-gui-mail-filter-when-objects.png[]
+
+WHEN - objects are use to activate rules at specific daytimes. You can compose
+them of one or more time-frame items.
+
+The default ruleset defines 'Office Hours', but this is not used by
+the default rules.