The Pack object is used to generate EntityContainers and fill them with incoming entities.
EntityContainers are created automatically on demand by the Pack object. The number of entities to be packed in each EntityContainer is determined by the NumberOfEntities keyword. Once the specified number of entities is available in the Queue, the entities are packed one by one in the EntityContainer in the same order as the Queue. The time to pack each entity is specified by the ServiceTime keyword.