Origin is the date-time for 1970-01-01 GMT in POSIXct
format. This date-time is the origin for the numbering
system used by POSIXct, POSIXlt, chron, and Date classes.
Usage
origin
Arguments
format
POSIXt[1:1], format: "1970-01-01 01:00:00"
Details
The original implementation of this 'object' is in the
lubridate package.