Boundary locking

Area protection is a type of blocking that only makes sense for multi-level area hierarchies. It ensures that the area and thus the outer boundary of superordinate territorial units remain unchanged, while boundary shifts are permitted within the area. In the case of a territorial structure containing districts consisting of postal code areas, where the districts are grouped into regions, one could, for example, place individual or all regions under area protection. If one then carries out an area optimisation at the district level, it is ensured that the external borders of all protected regions remain unchanged, while the borders between the districts within a region can be changed.

Please note that in the case of territorial organisations that extend over several levels, the protection of areas at a higher level means that border shifts within these areas are perfectly permissible.

Example:Region "North" contains the districts A, B and C. A certain number of postal codes is assigned to each carrier route. If the region "North" is placed under land protection, its total area cannot be changed. However, border shifts between the districts are permitted. New districts may also be added to the region or districts may be deleted. The only condition is always that the total area of the northern region does not change.