utc gps local
utc: Universal Coordinated Time (previously called GMT or Greenwich Mean Time).
gps: Global Positioning Satellite time. 24 equal hour clock time that has been determined by the GPS receiver from the transmitted 29 bit Z count. Time determination is accomplished by multiplying the GPS TOW (time of week) count by 1.5 to determine the number of elapsed seconds from the most recent Saturday midnight. A UTC offset can be applied by the receiver for local time. GPS time differs slightly from UTC time in that it does not account for the leap seconds that have accumulated since the GPS start time of midnight January 5, 1980.
local: Local time is the time provided by a given computer system or watch of the person making the observation. It does not carry the accuracy associated with GPS or UTC time. It can, however, be supplied with a UTC offset which approximates the equivalent Greenwich Mean Time.