A method and apparatus adapted to calibrate a signal path of a signal analysis system such that loading effects of the system are substantially removed from measurements of a device under test. Display material can be easily changed within a smooth non-damaging holder portion which opens for free non-friction insertion of the display material. In a ready state of the drug delivery device, the button member and the body are aligned and the alignment is perceivable by a user of the drug delivery device. The cores are connected to an interconnect structure that links the functional debug logic elements. The tag data includes an identification number used to identify the tag associated with a particular sign, price, marketing material or shopper, status data, and time and date information.