Boundary case

The term boundary case is frequently used in software engineering to refer to the behavior of a system when one of its inputs is at or just beyond its maximum or minimum limits. It is frequently used when discussing software testing.

For example, if an input field is meant to accept only integer values 0 - 100, entering the values -1, 0, 100, and 101 would represent the boundary cases.

See also corner case and edge case.