See L<rrdgraph> documentation.
+=item B<--enumds>
+
+The generated xml should contain the data values in enumerated tags.
+
+ <v0>val</v0><v1>val</v1>
+
+=item B<--unknwonaszero>
+
+Turn UNKNWON into '0' on output.
+
=item B<DEF:>I<vname>B<=>I<rrd>B<:>I<ds-name>B<:>I<CF>
See I<rrdgraph> documentation.