[freehunter]

The problem with programming for a leap second is you don't know when a leap second will occur. Compare this to a leap year, which happen every 4 years, always. Leap seconds are sporadic [1]. Programming a clock to accept the time of 11:59:60 only on occasion is trivial in a web app, but slightly more complex in a firmware or high-reliability system like flight controls.

[1] https://en.wikipedia.org/wiki/Leap_second#Insertion_of_leap_... (see the chart at the side)

[kamjam]

Thanks for the explanation, makes sense. I see what you mean about the sporadic nature of the insertions!