Each definition can have multiple, different definitions, called "fallthroughs". A fallthrough definition is applied is the first definition produces a null result. To add a fallthrough definition:
1. Select a data category in Definitions.
2. Hover over the plottable item to which you would like to add a definition and click the pencil icon. This will open the Definition Editor. Here, you can see the name, the format, the location and the ID of the plottable. Current definitions are visible in the first line of the definition box.
3. Hit +Definition to open a new definition field. Select the metrics that should be used to calculate the fallthrough definition. Hit Save.