What enables service item to be auto consumed into a work order?

According to the Oracle SCM Business Process Certified Foundations Associate Rel 2 document1, assembly pull is the supply type that enables service item to be auto consumed into a work order. Assembly pull means that material is automatically issued to a work order when it is completed. Service item is a type of item that represents a service or activity that is performed on or for another item, such as installation, repair, maintenance, etc. Service item can be auto consumed into a work order if it is defined as an assembly pull component in the bill of material.