A method for recognizing an obstructed situation of a traveling element. The present invention relates to a printed wiring board including: an insulating layer; and a signal layer including a set of at least two signal lines and disposed on one side of the insulating layer. The method receives a user request to access the stored data elements, compares the set of user security label components to the set of data security label components associated with the users, and based on the comparison result, determines whether or not to permit access to the stored data. The light-spreading device includes a wing-shaped protrusion part, a light incident surface, a recess located away from the light incident surface, and an optically-conditioning surface including a wavelike array, wherein the wavelike array has a wavefront direction. The unit quickly folds out into a fully supporting work bench for actual use of the saw andor equipment.