Academic Sessions represent time segments of your school year (i.e. semester, term, marking period). Generally, this file starts with a school year that is divided into terms. Although the IMS specification does allow for other units like semester, a term is what classes are assigned to, so it is the basic unit. You can, however, make a “term” and call it “Semester 2” if that is the appropriate word in your situation.
Note: sourcedIds for academicSessions should be unique across the entire data set.