When several plots are contained within a database, you may wish to modify one of the values on all of the plots. For example, you may wish to change the axis titles so that they are all the same. You can modify one plot so that it has the desired values, and then apply those modifications to the other plots, or a subset of the plots, in one step. When you modify xy plots using the panels of the xy plots module, the plot = field allows you to select one plot and the plots entity selector allows you to select multiple plots.