# Summary: Using the Iteration Hierarchy¶

This tutorial introduced the iteration hierarchy, a powerful concept which allows you to form arbitrarily complex process models. Some of the key points are summarized here:

* The top driver in an assembly is always called "driver"
* An assembly can contain multiple drivers
* Every driver has a workflow
* Workflows can contain multiple components (assemblies, drivers)
* A component instance can appear in multiple workflows
* Execution order in a workflow is inferred from the data connections
* If there are no data connections, execution order in a workflow is the order the components were added to the workflow

You have now completed the more complex tutorial problem.

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Working with Parallel Computational Resources