Piezoelectric elements 10 and 10 are driven so as to satisfy the relationship. The plug component can be contacted mechanically and electrically with a plug via the contact section. The present invention also relates to methods of treating a patient with such a dosage form, as well as kits containing such a dosage form with instructions for using the dosage form to treat a patient. A residual amount of an ink is indicated without being excessively affected by any disturbance such as the surface tension of the ink. The presence of related entities in the context of the candidate may be used to disambiguate the meaning of the candidate.