2.11.2 Abstract

Points in time are represented as the number of seconds (with nanosecond precision) since “the epoch”, a zero point in time. Several standard variants are defined, including UTC (Universal Coordinated Time), TAI (international atomic time), and monotonic time. A point in time can also be represented as a Julian Day or Modified Julian Day number.

Time durations, including time spent in a process or thread, are defined. Conversion routines are provided. The procedure current-time queries the current time in a specified variant, with a system–dependent resolution. Procedures for time arithmetic and time comparisons are also provided.

A date is a representation of a point in time in the Gregorian calendar, a 24 hour clock (with nanosecond precision) and a time zone offset from UTC. Procedures for converting between time and dates are provided, as well as for reading and writing string representations of dates.