A key attribute is the attribute used to find a specific row in a table of attributes when there is more than one instance of a set of attributes in a particular group. For instance, a computer system often has more than one serial port attached to it. To describe these serial ports, the Serial Port Group in the system's MIF file would be set up as a table, with one row in the table describing the specifics of a particular serial port. To access this information, one or more of the attributes (such as the I/O address) would be designated as the key. To find a specific serial port, the management application would ask for the row containing the proper I/O address.