data terminator

In computing, a special value used to mark the end of a list of input data items. The computer must be able to detect that the data terminator is different from the input data in some way – for instance, a negative number might be used to signal the end of a list of positive numbers, or ‘XXX’ might be used to terminate the entry of a list of names. This is now considered to be very bad programming technique. A lot of old programs used data terminators, and many programmers used 00 as a year data terminator, leading to problems in the year 2000.