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validity checking

Routines in a data entry program that test the input for correct and reasonable conditions, such as account numbers falling within a range, numeric data being all digits, dates having a valid month, day and year, etc. Checking the spelling of proper names, if possible, can also be part of validity checking. See validate for a comparison of "validate" and "verify."

Errors Can Be Critical
It may seem like a dull part of the IT world, but data entry validation can be a very critical issue when there is insufficient validity checking of the input. In late 2001, a Japanese stockbroker erroneously placed a sell order for 610,000 shares of stock at 16 yen, when it should have been for 16 shares at 610,000 yen. Even though the error was caught two minutes after the order was placed, the broker's liability was estimated to be up to USD $100 million.


To prove something to be sound or logical. Also to certify conformance to an accepted standard. Contrast with verify.

For example, data entry validity checking determines whether the data make sense (numbers fall within a range, numeric data are all digits, etc.), but "validity" checking does not "verify" that the data are correct. Even if the check digit in a customer account number is determined to be a valid number, it may still be the wrong number for that individual. In practice however, the terms "validate" and "verify" are often used synonymously. See validity checking, check digit and HTML validator.

Errors Can Be Laughable
Validating data typed into the computer is not a complicated concept. However, with regard to proper names, if there is no existing database to compare to, validation is a time-consuming job. The only way to ensure correct spelling is to have two different operators type the same name twice or to have a person visually compare what has been typed by another.

Is That Really the Name?
Residents of Everittstown, New Jersey would surely get a chuckle if they were driving a car in their town with this GPS navigation system. Of course, if the error was ever reported, an updated DVD disc would solve the problem.

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