Changing the primary key of a functional location means changing the label of the functional location. The label is the unique identifier of the functional location and it consists of a structure indicator and a functional location identification. The structure indicator defines the allowed characters and the hierarchy levels of the functional location structure. The functional location identification is the actual name of the functional location. When youchange the primary key of a functional location, you can either change the structure indicator or the functional location identification, or both. If you change the structure indicator, you need to adjust the functional location identification accordingly. If you change the functional location identification, you need to decide whether the functional location is assigned to a new superior functional location or not. A superior functional location is the functional location that is directly above the current functional location in the hierarchy. For example, if you have a functional location FL-01-02-03, where FL is the structure indicator, 01 is the first level, 02 is the second level, and 03 is the third level, you can change the primary key to FL-01-02-04, which means changing the functional location identification within the same level. In this case, you need to decide whether the functional location is still assigned to FL-01-02 as the superior functional location or not. Alternatively, you can change the primary key to FL-01-03, which means changing the functional location identification to a different level. In this case, you need to decide whether the functional location is still assigned to FL-01 as the superior functional location or not.

The user does not need to define a new labelling system for the new primary key, as the labelling system is defined by the structure indicator, which can be reused for different functional locations. Therefore, answer A is incorrect. The functional location can be assigned to a new superior functional location when the new label is entered, as long as the new label is consistent with the structure indicator and the hierarchy rules. Therefore, answer B is also incorrect. Changing the superior functional location via alternative labeling is possible, as alternative labeling allows you to assign different labels to the same functional location. Therefore, answer C is also incorrect. References: Explaining Technical Asset Structures - SAP Learning, Organizational Elements and Structures | SAP Help Portal, and SAP Alternative Labeling of Functional Locations.