In addition to nodes and links, a logistical performance cycle requires inventory. Within nodes, inventory is stocked or flows through the node, necessitating a variety of different types of material handling and at least limited storage. Performance cycles become dynamic as they accommodate input /output requirements. The input to a performance cycle is an order that specifies requirements for a product or a material. A high volume system will typically require a variety of different performance cycle arrangements to satisfy overall order requirements. When requirements are highly predictable or relatively low, the performance cycles required to provide logistical support can be simplified. For example, the overall performance cycle structure required to support a large retail enterprise like Wal-Mart is far more complex than the operating structure requirements of a direct mail-order company.