Assume that a unit of output is the cost object.

Royalties paid on per unit basis are an example of an indirect expense.

Materials consumed in the maintenance of machinery used to manufacture several different products are an example of a direct material cost.

The salaries of supervisors who oversee the manufacture of several different products are an example of a direct labour cost.

Rent paid for a factory in which several different products are produced is an example of an indirect expense.