The IL editor (SEdit) is the most flexible and powerful tool with which PCD controllers can be programmed. IL stands for instruction list: a non-graphical programming environment where the user writes programs with the help of the powerful PCD instruction set. All PCD controllers use this instruction set, thereby guaranteeing portability of programs from one PCD to another. The IL editor is more than just a valuable aid to program editing, it is also a diagnostic and on-line testing tool.