An examination supervision counts positive for a teacher by default, however, the periods cancelled due to this count negatively.
In the settings for the substitution planning in the "Substitution counter" area, you can select the option: "Count exams in a neutral manner". Then neither the cancellation is counted negatively, nor the examination positively, as long as the supervision teacher is the same as the teacher of the original lesson or the supervision teacher has a cancelled lesson due to the examination.
Examination supervisions of teachers held in their free period, i.e. they would not have had to teach a lesson, are continued to be counted positively with this option.