What term is used for test data on the boundary of what a program will accept?

The term used for test data on the boundary of what a program will accept is known as extreme data. Extreme data typically refers to the input values that lie at the limits of valid input ranges. This often includes values that are just above or just below the acceptable limits, allowing for testing of the program's behavior under edge cases. Testing with extreme data is crucial because it helps identify any potential issues or bugs that may arise when the program encounters values at the boundaries of expected input.

In the context of normal data, this refers to typical values that fall comfortably within the expected range, which does not adequately challenge the program's limits. Erroneous data, on the other hand, consists of inputs that are expected to be invalid or incorrect, while invalid data is any input that does not conform to the expected format or range. These types of data primarily test error handling rather than the boundaries of valid input. Therefore, extreme data is the most suitable term for testing inputs at the edges of what a program can accept.