A light guide plate includes an incident surface on which light outputted from point light sources is incident and an outgoing surface for outputting light incident from the incident surface, wherein a reflection-and-propagation surface for reflecting light toward the outgoing surface is formed in a back surface opposite to the outgoing surface. When changes are made to the user collection for a particular contact, the system detects the change, and based upon a number of administrative rules determines whether the change should be contributed to the firm collection. The reflector device has a first lateral surface, a second lateral surface parallel to the first lateral surface, and a rod surface extending from the first lateral surface to the second lateral surface. The cover has at least one aperture, with the first gripping device capable of extending through the at least one aperture. To specify a stationary blade for which there is no mechanical damage during turbine operation it is proposed that the inset extends into the recess so that in the base area of the inset there are zones with reduced predefined flow rates. The snap gesture is quantified with data elements including linger time and direction of the snap gesture.