This example tests whether a date/time value exists, and, if it does not, it creates a new pbdate object and sets its value to the beginning of January, 1900:

if (ci->pArgs->GetAt(i)->IsNull())
{
   pArguments[i].datetime_val=Session->NewDateTime();
   Session->SetDateTime(pArguments[i].datetime_val,
      1900, 1 , 1, 1, 1, 1); // Datetime:
                             // 1900-01-01 01:01:01
}
else
{
   pArguments[i].datetime_val = 
      ci->pArgs->GetAt(i)->GetDateTime();
}