WorldServer supports reuse of workflows by embedding one workflow within another. A Sub-Workflow Step contains the other/reused workflow. A Sub-Workflow has a result of Success or Failure that is used and affects the main workflow when the sub-workflow steps completes.
When you choose a Sub-Workflow Step, the workflow to be embedded must already exist and it must end with the Set Return Value automatic action. When the sub workflow terminates, it sends failure or success to the parent workflow, which can then branch accordingly.