I just found this in the ACE_Time_Value.h header.
// Static constant to remove time skew between FILETIME and POSIX // time. POSIX and Win32 use different epochs (Jan. 1, 1970 v.s. // Jan. 1, 1601). The following constant defines the difference // in 100ns ticks. // // In the beginning (Jan. 1, 1601), there was no time and no // computer. // And Bill said: "Let there be time," and there was time....
I wonder why Microsoft chose that epoch. Or why Posix chose theirs. 1970 seems way too recent to be a good epoch.