If you lock the timetable conditionally, the next optimisation run will skip the placement run and only carry out a swap run. This means that the resulting timetable will be very similar to the previous one. This constitutes an even higher level of similarity than the highest similarity setting (4 = great similarity) in the function described above. Use this function when you have carried out manual changes in the scheduling dialogue and want to start another optimisation run. Ticking this option means that your manual changes will be preserved.

When you combine the two previous functions by ticking the box "Lock timetable conditionally" and increasing the percentage under "% of periods to be scheduled", the software proceeds by first locking the previous timetable, then scheduling the remaining periods and finally carrying out a swap optimisation run for all the periods.