sentinel value
(sen´t&-n&l val´ū) (n.) In programming, a special value that is used to terminate a loop. The sentinel value typically is chosen so as to not be a legitimate data value that the loop will encounter and attempt to perform with. For example, in a loop algorithm that computes non-negative integers, the value "-1" can be set as the sentinel value as the computation will never encounter that value as a legitimate processing output.
Also referred to as a flag value or a signal value.


