At 09:24 -0500 on 01/10/2012, John Gilmore wrote about Re: 128-bit arithmetic:
No use of the TIME macro need or should figure in this operation. Any leap-second corrections would, for example, be washed out by the subtraction: (T + L) - (t + L) = T + L - t - L = T - t.
Only if the interval t-->T does not span the introduction of the Leap Second. If t is in Year X and T is in Year X+1 then if the last minute of year X is 61 seconds long, your interval T-t will be off by one second.
