An optional, brief description of the key.
In environments that support delegation, looking up this key when it has no associated value will delegate to the values associated with these keys.
Specifies whether this key is a local, anonymous key (
true) or not (
The label is the identifier for the key and is camelCase by convention.
The runtime evidence for
Identifies the relative importance of a key among other keys.
(Since version 0.13.0) Should only be used for compatibility during the transition from hyphenated labels to camelCase labels.