When does a generic resource get added to a task?

A generic resource gets added to a task when the project manager performs any of the following actions:

• Specifies planned effort against a task and saves the project plan. When this action is performed on a task that doesn't yet have any planned resources, a labor resource is added to the task with the specified effort. Similarly, if you specify the plan amount, a financial resource is added to the task with the specified planned amount.
• Explicitly creates the planned resource or converts an unplanned resource to a planned resource when the costs comes in from a higher resource level. For example, Labor or Labor: Professional.

Note: The application doesn't automatically add a generic resource to a task.