A slotted drain having a first channeled half having a first engaging structure and a second channeled half having a second engaging structure mating within the first engaging structure is disclosed. Certain layers may carry patterned electrodes that are arranged to permit their connection to an electrical interrogation circuit. An in-camera parameter, an in-projector parameter, a parameter of positional relationship between the camera and the projector are estimated. The delivery system includes a valve covering member and a compressing member, which compresses the valve covering member to surround, hold, andor compress the valve during delivery to the target area. Packages comprising these articles are also disclosed. If the new state is a known state that represents a hit state, the system would map the change of state to a key hit in a row and column of the keyboard and sends the function associated with that key for execution.