Comments can be added to each resource requirement to briefly explain what it does.
Check for a file then wait if not found
This is typically used when a job needs some data to be available to be able to do its processing.
If the specified file doesn't exist when the job is submitted, the job will wait in the "Waiting for resources" (H) queue. The schedule server checks periodically jobs in that queue and once the required file is present, it will evaluate the remaining resources of that job.