CDP It is extremely improbable that a large computer system has ever been created completely error free.
Complex programs have higher error probabilities than simpler ones.
The primary purpose of a software system is ease of use. Therefore, the ratio of function to conceptual complexity is the test of good system design. Neither function nor simplicity alone defines a good system. This implies that a user can tolerate a number of errors in a software system provided that the system is functional. Often, during testing, it is discovered that many apparent errors are due to incorrect specifications.