By default, no key is assigned to act as a third-level modifier. You can assign a key to act as a third level modifier in the Keyboard Layout Options Preferences.
Lehenespenez, ez da teklarik esleitzen hirugarren mailako aldatzaile gisa jarduteko. Tekla bat hirugarren mailako aldatzaile gisa esleitzeko, erabili Teklatuaren diseinuaren aukera-hobespenak.