Parent Tasks are the composite and decorator tasks within the behavior tree. While the ParentTask API has no equivalent API to Unity’s MonoBehaviour class, it is still pretty easy to determine what each method is used for.

// The maximum number of children a parent task can have. Will usually be 1 or int.MaxValue
public virtual int MaxChildren();

// Boolean value to determine if the current task is a parallel task.
public virtual bool CanRunParallelChildren();

// The index of the currently active child.
public virtual int CurrentChildIndex();

// Boolean value to determine if the current task can execute.
public virtual bool CanExecute();

// Apply a decorator to the executed status.
public virtual TaskStatus Decorate(TaskStatus status);

// Notifies the parent task that the child has been executed and has a status of childStatus.
public virtual void OnChildExecuted(TaskStatus childStatus);

// Notifies the parent task that the child at index childIndex has been executed and has a status of childStatus.
public virtual void OnChildExecuted(int childIndex, TaskStatus childStatus);

// Notifies the task that the child has started to run.
public virtual void OnChildStarted();

// Notifies the parallel task that the child at index childIndex has started to run.
public virtual void OnChildStarted(int childIndex);

// Some parent tasks need to be able to override the status, such as parallel tasks.
public virtual TaskStatus OverrideStatus(TaskStatus status);

// The interrupt node will override the status if it has been interrupted.
public virtual TaskStatus OverrideStatus();

// Notifies the composite task that an conditional abort has been triggered and the child index should reset.
public virtual void OnConditionalAbort(int childIndex);