An LPL can either be created explicitly (teacher and class are known) or they are created as a result of an incomplete substitution (e.g. displaced lesson).
•Creating LPLs explicitly
•LPLs from lessons
•LPLs from the timetable / scheduling dialogue
•LPLs from displacements
•LPLs from substitutions
•Changing LPLs
•Deleting LPLs