Available in Sage 50 Premium Accounting and higher.
This window is where you set up phases to be assigned to jobs. You can't assign a phase to a specific job here, but you can set up the phases that will be available for all jobs.
What are phases and why should I use them?
In Sage 50, you do this when you actually enter the costs, rather than when you create the job, phase, or cost code. So when you set up Sage 50 for your jobs, you will separately set up all of your jobs, then all of the various phases (parts) of your jobs, then all of the specific types of costs (cost codes) for each aspect of the work you will perform.
Then, when you purchase, say, materials for a job, you will enter the job, phase, and cost code that the materials were used for in Purchases/Receive Inventory, on the line item for that purchase. Internally, Sage 50 will keep track of which job, phase, and cost code were used and report on the job appropriately.