Practical options for time tagging

Abstract

The international timekeeping community prepares several official timescales, and there exist a plethora of alternatives used by others, often with no official recognition. The advantages and disadvantage of several official timescales are presented; however, they are all interconvertible using information readily available on the internet. A discussion of traceability and the statistical errors is included; all of these scales are ultimately traceable to UTC. Many of the considerations are not relevant if the error tolerance is above a few tens of nanoseconds.