Additionally, SSN should never be used as a key as duplicates do exist.

>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