Indicates whether metrics for this particular label type represent an
aggregate of metrics for other types instead of being based on actual
TP/FP/FN values for the label type. Metrics for parent (i.e., non-leaf)
entity types are an aggregate of metrics for their children.
The metrics type is unspecified. By default, metrics without a
particular specification are for leaf entity types (i.e., top-level
entity types without child types, or child types which are not
parent types themselves).