-If specified, only specific plugins are flushed. Otherwise all plugins
-providing a flush callback are flushed.
+If the B<plugin> option has been specified, only the I<Plugin> plugin will be
+flushed. You can have multiple B<plugin> options to flush multiple plugins in
+one go. If the B<plugin> option is not given all plugins providing a flush
+callback will be flushed.
+
+If the B<identifier> option is given only the specified values will be flushed.
+This is meant to be used by graphing or displaying frontends which want to have
+the lastest values for a specific graph. Again, you can specify the
+B<identifier> option multiple times to flush several values. If this option is
+not specified at all, all values will be flushed.