open studies is when the student has not yet been enrolled in the college/uni but is taking courses outside of the program, these courses will be considered completed when they do take admission into it.
For eg. if you are enrolled for Fall 2015 but you want to take some classes in summer 2015 and spring 2015 so that you finish your program quicker. You cannot do so because the program intake is fall 2015. However, open studies lets you take them as outsider (not enrolled yet) and then counts it in later when you do enroll.