Tandem time starts in 4700BC in micro seconds.

This is the whackiest time format I have ever heard of, I wonder what they were taking^Wthinking.

You want to convert to epoch seconds, then add 4700 + 1970 years worth of seconds and then multiply by 1000.

The 4700+1970 years worth of seconds is the sticky part- you have to take into account all the leap years and pretend that the calender doesn't change as you go back. I would bet they have a pre-calculated constant they cut 'n paste around.

See Time::Local and localtime() for converting to/from epoch seconds.

--
Until you've lost your reputation, you never realize what a burden it was or what freedom really is. -Margaret Mitchell

Also, remember that there was no year 0. (not that our current calendar was in use back then, but the scholars have had their say) Dec. 31, 1 BC was followed by Jan. 1, 1 AD. At least thats what I remember from the 2000/2001 end-of-the-millenium debate.

-Blake