An integral part of project management is the management of expenses and proceeds. Expenses in project business usually arise from "external services" by freelancers or the acquisition of "proprietary code" for ones software. Added travel expenses and possible costs for commision of mediated orders. All of these expenses are accounted for as supplier invoices. Furthermore expenses may arise for shares in costs (rent, electricity costs, etc) as well as for employees that work on projects salaried.