A teacher’s workload is not restricted just to teaching - it includes other duties, e.g. school management, supervision of teaching materials, subject mentoring, library administration etc. Such duties can be taken into account by creating reductions.
Reduction reasons
You must first enter reasons for reductions under “Master Data | Reduction reasons”.
The figure below shows the reduction reasons from the file Demo2.gpn. Please note that reduction reasons can be grouped into categories with the aid of the "Description" field. This can be extremely useful when selecting reduction reasons subsequently (for statistical analysis).

Reductions themselves are entered in the “Lessons | Reductions” window.

The figure shows you the reductions for teacher Hugo. For his mentoring duty as class teacher ('CTe') he is credited with 2.000 value units (if you work without value calculation, the number of periods for the week are used). He is also credited with 1 value unit for supervision of the physics collection (reduction reason: PhS ).
If you wish to display the reductions for individual teachers (as is the case in the figure) using the corresponding selection list, you will see how many value units have already been allocated to the teacher.
For teacher Hugo, 3.000 value units in the form of reductions and 21.681 value units of lessons have been assigned. This results in a total of 24.681 value units. Hence 0.319 value units are missing from his total weekly target of 25 value units.
Using drag & drop with teachers and reduction reasons
You can use drag & drop to assign one reduction reason (e.g. mentoring) to several teachers in the element window ('Master Data | Element Rollup'). To do this, use CTRL+click to mark the teachers concerned and drag them into the reduction reasons window.
In the example, several teachers are assigned a reduction for mentoring as class teachers ('CTe').

You will now find all the marked teachers under 'CTe' and you can enter values for them.

Conversely, several reduction reasons can be assigned to one teacher.