The Peircean sign is a triadic relation that connects an object, O, to a representamen, R, and then to an interpretant I. The triadic sign relation provides a tool for showing conceptual relationships. In the case of a radar system, for example, the actual aircraft would be the (Dynamic) object, the representamen (Immediate Object: mental image) is the track symbol or a blip on a display, and the interpretant is the radar operator. The User's quality measures.SourceBy manipulating signs, we refer to the Dynamical Object as a terminus ad quem of semiosis.
terminus ad quem is a Latin phrases for "limit from which" and "limit to which;" hence, the temporal starting-point and ending-point for the occurrence of any event, the moments of its beginning and its completion.Source