audot code. Data transmission code which uses five bits for puter source code into machine level binary object code. character representation. Now rarely used. Asynchronous. It defines the process for communications in Baud rate. It is a measure of the speed of transmission of binary which the transmission is not tied to a particular frequency or data, and is equal to the maximum number of symbols gener- timing pulse. Some form of start and stop information is added ated per second. to the transmitted information, to define its content and provide Beam splitter. A device, used in optical transmission, for splitting timing for the receiving end. an optical beam into several other beams. AT command. Protocol used between modems and terminals to Behaviour. This is usually used in the context of managed objects allow for testing, reconfiguration and autodialling of the within network management sytems. It is the sequence of modem. attributes and notifications which are exhibited by the managed Attenuation. A measure of the loss of a signal strength, usually object due to the occurrence of management operations. measured in decibels. Bell Atlantic. One of the seven regional Bell operating covering Attenuator. A device which reduces the signal strength between the mid-Atlantic region of the US. two points during transmission. Bias. Usually refers to a voltage which is applied to a circuit or Attribute. This is a value which defines the property of an object component. within an object orientated system. Binary channel. A channel used for transmitting binary digits. Audiotex. A system used to provide published information (e.g. Binary coded. A coding system which uses binary numbers to weather forecast) to callers over a telephone. represent transmitted information. Autoanswer. The ability of a terminal, such as a modem, to auton- Binary symmetric channel. A transmission channel in which the omously answer a call over the switched telephone network, probability of error is the same for zeros and ones. and to set up a ro