I believe there will be subject related questions and may be about 80 percent of the total interview. They will ask about your specialization and then questions form your specialized area. They will ask about your current and future jobs and the tasks you performed during those jobs, about your education, why you want to leave your current job, and what you expect from your new job etc.
This is just an idea that how interview might progress. Please do share your experience so that others can benefit as i have an interview as IT officer so i believe that they will ask similar questions..