Verify data as it is entered. The i

Verify data as it is entered. The input design should specify a data type, such as
alphabetic, numeric, or alphanumeric, and a range of acceptable values for each
data item. If an incorrect value is entered, the system should recognize and flag it
immediately. The system also should allow corrections at any time. Some errors,
for example, can be easily corrected while the
original source documents are at hand or the
customer is on the phone. Other errors may
need further investigation, so users must be
able to correct errors at a later time.