mktime, how to handle dates before 01-01-1970 ?

[Stef Mientki]

hello,

I want to handle datetime vars in a general way, so I use the default 
time-format,
so I can use the standard cinversion procedures.
Time format is the time difference since 1-1-1970.

So how do I handle dates before 1-1-1970 ?

I'ld expect times before 1-1-1970, simply to become negative numbers
(I'm interested in the age of living people, so that would suffice).

Is there a general solution, (other library)
or would it be better to handle all dates in the Delphi format (number 
of days since  1-1-1900

thanks,
Stef Mientki