You can hold, resume and cancel Jobs in Worldserver.
For example, you might want to place a job on hold if you want it to run after other jobs run (another way to handle this situation is to change the priority of the job). You might also want to place a job on hold if you are waiting for resources to be available before the job runs.
Remember that a job on hold will never run. It is a good practice to occasionally check the Job Views, my jobs on hold or all jobs on hold to verify that jobs are not left on hold indefinitely.