When you create your Annual Personal Study Plan (APSP), first of all you must include your incomplete courses (with exam still pending). Incomplete courses are the courses contained in your APSP of previous years for which you have not passed the exam yet, or, your grade has not been recorded in your trascript yet. These courses are marked in blue by the system. They need to be included in your APSP before adding any new course for the first time.
A full-time workload APSP can include up to a maximum of 80 credits.
A part-time workload APSP can include up to a maximum of 40 credits.
If you add some extra courses and exceed the maximum limit, these courses are called overbooking courses (marked in red).