(current-time)
Returns a rational number representing the current number of milliseconds (excluding milliseconds during a leap second) since the Posix Epoch, which is 00:00:00 on 1 January 1970, Coordinated Universal Time. Implementations SHOULD return a value that is as precise and accurate as possible. Implementations MAY return exact or inexact values, and SHOULD return inexact values unless:
In practice this means that implementations with fixnums greater than 253 should return fixnums unless they have time-of-day clocks that provide more than 1 ms precision, and all other implementations should return IEEE 64-bit floats.
See TimeAdvancedCowan.
See TimePeriodsCowan.