What exactly are "data plot style holders" and what do they mean for me? I've noticed that all of my line plot templates have 9 line data plot style holders and 1 text data plot style holder. They're even there when I open the template as a template file (no data plotted).
When a graph is saved as a template, all the data plot's settings are saved into internal objects call these style holders. When you add new data to a layer, it will pick up the next style holder so the newly added plot will have all the settings applied to it automatically, and this is how templates work, you save a template, plot new data into it and everything will look they way the plots were supposed to look.