Process group labels exist to provide the developer with an abstract method of determining job relationships independent of the job name or job ID relative to the process group ID.
In order to support this, the jobs must all be submitted under the same process group ID either by submitting the jobs in the same API call, or by attaching the job to a process group upon submission.
The system automatically checks for the uniqueness of the process group label, and will automatically assign unique labels to jobs which don't have labels. Once the jobs are all in the same process group, each job is allowed to reference each other by using their labels.
Example
done-job-hello
running-job-world