Some teachers are rather not, or not at all to be assigned to substitutions (e.g. external teachers), however, others are preferrably assigned to substitutions. You can define such requirements yourself, and they will be applied in the substitution suggestion as decision criteria.
This column shows a statistics code which has been entered in the teachers' master data. If you use this field appropriately, it can provide you with useful information. If, for instance, you mark foreign teachers with "F" and part-time teachers with "P", you immediately have the information , whether you actually can reckon with the availability of a teacher who in general is "off duty".
If you go to "Teachers | Master data | Subst.", availability is shown.
In many a case, it is preferred that, if a teacher who in general is available for substitutions, is nevertheless not assigned for substitutions.
You can use the "Availability" field to obtain this effect. You have a scale from 0 to 9, 9 means it is absolutely prohibited to assign this teacher to substitutions. If you leave this field empty, which is synonymous to "0", this means that the teacher has no substitution restrictions what so ever. 1 to 8 are to be used for grading.
You can define yourself in how far the availability has an impact on the order of the substitution suggestions compared to other factors (see chapter "Order of substitution suggestion").