I agree that an SSN should not be used as a PK, but it should be unique. If someone else uses the same SSN as you, your wages are reported incorrectly and there will be trouble when you retire. If the same SSN is used for more than one individual, it should be reported. The SSN Administration now sends out contribution statements annually and if someone does not receive one, then they need to contact the SSN to get it straightened out. In the majority of cases, duplicate SSNs exist due to identity theft (typically from illegal aliens making up an SSN to get employment more often than actual identity theft) and only a very small number are due to the administration actually issuing duplicates. When that happens, it is usually because the SSN thought the original holder of the SSN is deceased. Also, an SSN is typically required to get a job (not necessarily verified though and except for some visa circumstances) and in the financial world, a SSN is now required for financing. It is due to Homeland Security's Sarbane Oxley Act of 2002. If you finance your auto insurance you have to have either an SSN or an ITIN (individual taxpayer identification number). Also for financing school loans, purchasing weapons, and getting a commercial driver's license. Smaller businesses are still trying to comply with the Sarbanes-Oxley Act but most larger organizations have already met the requirement.

>Also keep in mind that a US SSN is not unique (there are cases of duplicate SSN beeing issued) so it is not reccomended to use the SSN as a PK.
>
>>Beware that SSN is considered "sensitive" data and if your system doesn't actually need it (i.e. for taxpayer identification), you might want to make it an optional field.
>>
>>Privacy concerns are high in the US and likely to get worse, and many people will refuse to give their SSN.
>>
>>Dan
>>
>>>Dear all
>>>
>>>I am translating my software to English and also making some
>>>structural changes to it in order to reach american users
>>>
>>>In Brazil our national indenfication document is CPF.
>>>CPF is a 11 digits string that has a logic and is possible to validate by a function.
>>>
>>>I would like to know if SSN is also a logic string, and a function in VFP is available to validade it
>>>
>>>Regards
>>>
>>>Moises