Stores and manages variables that will be used in constructing new [Blackboard] instances. Constructs a new instance of a [Blackboard] using this plan. If [NodePath] prefetching is enabled, [param node] will be used to retrieve node instances for [NodePath] variables and substitute their values. Populates [param blackboard] with the variables from this plan. If [param overwrite] is [code]true[/code], existing variables with the same names will be overwritten. If [NodePath] prefetching is enabled, [param node] will be used to retrieve node instances for [NodePath] variables and substitute their values. Enables or disables [NodePath] variable prefetching. If [code]true[/code], [NodePath] values will be replaced with node instances when the [Blackboard] is created.