For instance, the basic function of any signal is to impinge upon the environment in such a way that it attracts attention, as, for example, the dots and dashes that can be applied in a telegraph circuit. Coded to refer to speech, the potential for communication through these dots and dashes - short and long intervals as the circuit is broken - is very great. Less adaptable to the codification of words, signs also contain agreed upon meaning; that is, they convey information in and of themselves. Two examples are the hexagonal red sign that conveys the meaning of stop, and the red and white swirled pole outside a shop that communicates the meaning of barber.