Resources can be consumable or non-consumable. Examples of consumable resources are equipment or supplies such as trucks and gasoline. Examples of non-consumable resources would be a salaried employee or a hired consultant. Resources are defined on a per simulation basis and are available for all processes within a simulation -- meaning that a single pool of a resource is shared.

This allows a more sophisticated comprehension of resource contention across a set of processes in an enterprise. Resources are defined by the units allocated for the resource and the units acquired at a particular process step. A consumable resource acquired at a step is used and removed from the set of allocated resources. A non-consumable resource, such as an office clerk, when acquired is not available by other steps until the processing of that step is completed. This means that if you have only one office clerk and the step that requires the clerk is started, the next process instance that arrives at that step will be queued for processing until the first instance requiring the clerk is completed.