This exists, though it's rare to see any software that uses it. DJB's daemontools do, somewhat unsurprisingly. It's called TAI, International Atomic Time [0],

This exists, though it's rare to see any software that uses it. DJB's daemontools do, somewhat unsurprisingly. It's called TAI, International Atomic Time [0], and it's effectively just UTC minus the leap seconds. It's (close to) the actual time being measured by CPUs all about and it's a pain in the ass to convert to and from it due to leap seconds and such, but if you want to just make time somebody else's problem entirely then using TAI will keep you accurate at least. [0] http://en.wikipedia.org/wiki/International_Atomic_Time http://en.wikipedia.org/wiki/International_Atomic_Time