What's a default planning resource breakdown structure?

A planning resource breakdown structure consisting of one resource format (resource class) with four associated planning resources: Labor, Equipment, Material Items, and Financial Resources.

A default planning resource breakdown structure is created automatically for each project unit. When you create a project template, the default planning resource breakdown structure is selected as primary, but you can designate any other one. Once you designate, you cannot remove the planning resource breakdown structure from the project template or project.