In software systems for resource-constrained production planning, it is often beneficial to determine a detailed association, or \u201cpegging\u201d, between the resources and the shipments that are enabled by those resources. The application provides a system for recording flows on a fire appliance to address deficiencies in the prior art where such information is only analysed during an event. The holding portion includes an intermediate member guide which guides the intermediate member so that the intermediate member rotates.