My understanding of this Job Status is that the job completed, but Tidal was unable to determine if the job succeeded or failed. Simply put, this means operator intervention is required to determine the success or failure of the job. This can happen when a job is defined to Scan Output to determine success or failure and no output is generated by the jobs.
You could force a status of Externally Defined by checking "Extrernal" in the tracking area like a manual checkpoint requiring operator intervention or external process to set status (maybe via SACMD) to Completed Normally *
Otherwise as Tracy mention you can get this
if there is no output to be evaluated or output is still being gathered/written or not available at the time the job ends
Tidal Status defintion from help
If the status of a job occurrence is ExternallyDefined then Scheduler is waiting for an external status update.
We have also put emails on externally defined and this is what it comes up with (scan scenario):
Output for job XYZ [####] was not available to be scanned