 traffic carried over a single multilink bundle with bulk traffic. m-commerce (mobile commerce) Financial transactions that occur on mobile devices. MCU (multipoint control unit) A device that supports multiparty videoconferencing between several individual-circuit videoconferencing systems. The MCU acts as a videoconfer- ence hub. MD5 (Message Digest-5) An algorithm used to create digital signatures. MD5 is intended for use with 32-bit machines. It is a one-way hash function, which means it converts a message into a fixed string of digits called a message digest. (main distribution frame) A structure that contains all the necessary power and test equipment to support terminal strip connections and wiring arrangements that connect outside and inside telephone exchange circuitry. measured rate A message rate structure that includes payment for a specified number of calls within a defined area, plus a charge for additional calls. mechatronics A system that uses mechanics, electronics, and computing to generate simpler, more economical, reliable, and versatile systems. Automotive applications of mechatronics, for Glossary media filter example, include obstacle detection, door control, and climate control, as well as support for telematics and multimedia. media filter A filter used in token-ring lobe wiring to convert STP-only adapter cards to UTP wiring. media gateway A device that provides seamless interoperability between circuit-switched, or PSTN, networking domains and those of the packet-switched realm (i.e., IP, ATM, and Frame Relay networks). A media gateway interconnects with the SS7 network and enables the handling of IP services. MediaFLO A mobile TV standard from Qualcomm. MediaFLO is a comprehensive end-to-end solution that simultaneously and cost-effectively delivers very high volumes of high-quality, streaming, or clipped audio and video multimedia to wireless subscribers. medium (1) The material on which data is recorded (e.g., magnetic tape, CD-R). (2) Any material substance that is or can be used fo