Ditops is a resource-directed scheduling system that uses a beam search technique to schedule possibly thousands of time-dependent plans that utilize hundreds of resources. A plan enters Ditops as a set of demands for moving cargo (people are a type of cargo) from one location to another. Ditops uses these demands to create a set of activities that represent a process that when executed can satisfy the demands. These activities require resources and occur over some time interval. An activity can also be related temporally with other activities. Some of these temporal relationships are defined by the Prodigy planning activity. These Prodigy defined relationships come from the partial ordering of the demands that Prodigy encountered when creating the plan. The demands can be at various levels of abstraction.