If your customer claims that they are registered for VAT — but the verification through VIES does not confirm this — they can request verification with the tax office in their country.
Can anybody remind me of the arithmetical check that can be employed to validate a VAT number?
CAS Numbers are represented generally as a sequence of digits numbered right-to-left, excluding the rightmost digit, which is labeled "R".
Microsoft is conducting an online survey to understand your opinion of the Msdn Web site.
VIES is available in 23 languages of the European Union.
CAS Registry Numbers are used extensively in chemistry and commerce to identify chemical substances.
One reason is that CAS Numbers tolerate human data entry errors thanks to a built-in check digit. For example, the CAS number for Imatinib, , contains six digits in the first block, and a check digit of "5".
Long distance calling generally involved a human operator.
Modern American telephone numbers have ten digits, segmented as a three-digit area code, a three-digit exchange code, and a four-digit number.
In some situations, such as validating custom controls or supporting legacy browsers, additional scripting may be necessary to validate user input.