On 4/28/2011 2:59 PM, Steven D'Aprano wrote: > Still, it could be worse... I've seen a programs use 9999 to represent > missing values, on the basis that nobody could ever have more than (say) > 5000 invoices in the database... >> (I wish I was exaggerating.) All 9s in a field for missing was once standard for Fortran programs. -- Terry Jan Reedy