I added a section on nanoseconds:
http://www.limey.net/~fiji/perl/faq.html#2.9%3A%20How%20small%20an%20increment%20of%20time%20can%20I%20represent%3F
The raw POD is below.
I deliberately did not mention fractional_second since Dave suggests
that it is going away... If this is not true, please let me know and
I will add info on it.
-ben
=head3 How small an increment of time can I represent?
A<DateTime> can represent nanoseconds. You can create obects with
that resolution using the C<nanosecond> parameter to C<new> or C<set>
and there is a corresponding C<nanosecond> accessor. For these you
give an integer count of the nanoseconds.
A millisecond is a thousandth of a second (10^-3 or 0.001). The
abbreviation is I<ms>.
A microsecond is a millionth of a second (10^-6 or 0.000001). The
abbreviation is I<us> (or more properly I<E<micro>s>).
A nanosecond is a billionth (US) of a second (10^-9 or 0.000000001).
The abbreviation is I<ns>.
=for example begin
# The ns part is 0.000000230 below
my $dt_ns = DateTime->new(year => 2003, month => 3, day => 1,
hour => 6, minute => 55, second => 23,
nanosecond => 230);
print "ns: ", $dt_ns->nanosecond, "\n"; # Prints: "ns: 230\n"
# Assuming we got microseconds as an argument
my $ms = 42;
my $dt_ms = DateTime->new(year => 2003, month => 3, day => 1,
hour => 6, minute => 55, second => 23,
nanosecond => $ms * 1_000_000);
print "ms: ", $dt_ms->nanosecond, "\n"; # Prints: "ms: 42000000\n"
=for example end
=for example_testing
is($_STDOUT_, "ns: 230\nms: 42000000\n", "Nanoseconds");
