now_d_ps () is
(d, ps) representing the POSIX time occurring at
d * 86'400e12 +
ps POSIX picoseconds from the epoch 1970-01-01 00:00:00 UTC.
ps is in the range [
current_tz_offset_s () is the clock's current local time zone offset to UTC in seconds, if known. This is the duration local time - UTC time in seconds.