PPSC must add some quota in finance department,if they govt wanted some improvement in revenue system,otherwise after training everyone perform his duties or may be a person belong to arts,science etc,but see perfection in work only finance and commerce students.They know the ways in which how to save govt expenses and perform the works timely.According to my information in DDAO jobs mostly works related cheques and govt funds so thats work suit only commerce.Otherwise everyone perform functions.