The ideia is basically a page where you can manage common derived metrics formulas for your index (something like
scripted fields in Kibana's
index patterns page). Once the formulas are created, the user should be able to see them in a dropdown list when creating visualizations (instead of adding manually the same formula for each new visualization). This would be really helpful since the visualizations sometimes share the same derived metrics! Also, in my case, I have some derived metrics that relies on other derived metrics, so this would help us to keep this kind of complexity in one place only.
If you prefer, I can open an issue in the repo to discuss this feature (I also opened another issue about the table footer "total" calculation!).