A. A check digit allows the computer to automatically reject incorrect entries. The cumber-some computation required to establish the check digit, however, tends to limit its use to a few key entries. Check digits are never used to test accuracy of input for an entire grouping of input.

B. Sequence checking provides a reasonably good test for completeness of input but does not test accuracy.

C. Limit checks are useful to determine whether an entry is within acceptable limits only. Such limitation makes the limit check unusable to test the accuracy of input.

D. Batch total checks provide a reasonably good test for completeness and accuracy of input.