Ptime has platform independent POSIX time support in pure OCaml. It
provides a type to represent a well-defined range of POSIX timestamps
with picosecond precision, conversion with date-time values,
conversion with RFC 3339 timestamps and pretty printing to
a human-readable, locale-independent representation.

The additional Ptime_clock library provides access to a system POSIX
clock and to the system's current time zone offset.

Ptime is not a calendar library.