-# DBUS_ARG# (where # is the number from 0 to DBUS_ARGN) - arguments of event,
-# DBUS_ARGN - number of event arguments,
-# DBUS_SENDER - event sender name,
-# DBUS_DEST - event destination name,
-# DBUS_IFACE - event interface,
-# DBUS_PATH - event object path,
-# DBUS_MEMBER - called event member,
-# DBUS_BUS - bus event came from (`session' or `system'),
-# DBUS_TYPE - event type as described above.
+# DBUS_ARG# (where # is the number from 0 to DBUS_ARGN) - arguments of message,
+# DBUS_ARGN - number of message arguments,
+# DBUS_SENDER - message sender name,
+# DBUS_DEST - message destination name,
+# DBUS_IFACE - message interface,
+# DBUS_PATH - message object path,
+# DBUS_MEMBER - message member (a.k.a. method),
+# DBUS_BUS - bus message came from (`session' or `system'),
+# DBUS_TYPE - event type as described above,
+# DBUS_ERROR - error name if message is error message, empty string otherwise.