date_to_posix_time ~y ~m ~d ~hh ~mm ~ss ~ff ~tz_mm is the POSIX time corresponding to the calendar date y-m-d at time hh:ss:mm.ff with time zone offset tz_mm in minutes.
date_to_posix_time ~y ~m ~d ~hh ~mm ~ss ~ff ~tz_mm
y-m-d
hh:ss:mm.ff
tz_mm
Warning. Does not check ranges or that y-m-d is a valid calendar date.