Hi milos,
It looks like you're using Method for QuickBooks Online. In this case, I don't believe that the JobType table is currently in-use. If you're planning on building a custom workflow, I'd recommend that you instead create your own custom table for this.
It's always a possibility that Intuit will implement this table in the future for QBO. It's best practice to avoid using these currently not-in-use tables for custom data, as this could cause problems with the sync should the table ever be implemented in the future. I hope this helps.
--Audisho