I<vname> can then be used throughout the rest of the script. By
default, an B<RRA> which contains the correct consolidated data
at an appropriate resolution will be chosen. The resolution can
-be overridden with the L<--step|rrdgraph/item_Time> option.
+be overridden with the L<--step|rrdgraph/item_Time> option.
The resolution can again be overridden by specifying the B<step size>.
The time span of this data is the same as for the graph by default,
you can override this by specifying B<start and end>. Remember to