List of features. Default is the empty list.

A feature is string tag that can be enabled or disabled on a target. The meaning of a feature depends on the rule itself.

This features attribute is combined with the package level features attribute. For example, if the features ["a", "b"] are enabled on the package level, and a rule features attribute contains ["-a", "c"], the features enabled for the rule will be "b" and "c". See example.