ruby formatting time

%Y%m%d           => 20071119                  Calendar date (basic)
%F               => 2007-11-19                Calendar date (extended)
%Y-%m            => 2007-11                   Calendar date, reduced accuracy, specific month
%Y               => 2007                      Calendar date, reduced accuracy, specific year
%C               => 20                        Calendar date, reduced accuracy, specific century
%Y%j             => 2007323                   Ordinal date (basic)
%Y-%j            => 2007-323                  Ordinal date (extended)
%GW%V%u          => 2007W471                  Week date (basic)
%G-W%V-%u        => 2007-W47-1                Week date (extended)
%GW%V            => 2007W47                   Week date, reduced accuracy, specific week (basic)
%G-W%V           => 2007-W47                  Week date, reduced accuracy, specific week (extended)
%H%M%S           => 083748                    Local time (basic)
%T               => 08:37:48                  Local time (extended)
%H%M             => 0837                      Local time, reduced accuracy, specific minute (basic)
%H:%M            => 08:37                     Local time, reduced accuracy, specific minute (extended)
%H               => 08                        Local time, reduced accuracy, specific hour
%H%M%S,%L        => 083748,000                Local time with decimal fraction, comma as decimal sign (basic)
%T,%L            => 08:37:48,000              Local time with decimal fraction, comma as decimal sign (extended)
%H%M%S.%L        => 083748.000                Local time with decimal fraction, full stop as decimal sign (basic)
%T.%L            => 08:37:48.000              Local time with decimal fraction, full stop as decimal sign (extended)
%H%M%S%z         => 083748-0600               Local time and the difference from UTC (basic)
%T%:z            => 08:37:48-06:00            Local time and the difference from UTC (extended)
%Y%m%dT%H%M%S%z  => 20071119T083748-0600      Date and time of day for calendar date (basic)
%FT%T%:z         => 2007-11-19T08:37:48-06:00 Date and time of day for calendar date (extended)
%Y%jT%H%M%S%z    => 2007323T083748-0600       Date and time of day for ordinal date (basic)
%Y-%jT%T%:z      => 2007-323T08:37:48-06:00   Date and time of day for ordinal date (extended)
%GW%V%uT%H%M%S%z => 2007W471T083748-0600      Date and time of day for week date (basic)
%G-W%V-%uT%T%:z  => 2007-W47-1T08:37:48-06:00 Date and time of day for week date (extended)
%Y%m%dT%H%M      => 20071119T0837             Calendar date and local time (basic)
%FT%R            => 2007-11-19T08:37          Calendar date and local time (extended)
%Y%jT%H%MZ       => 2007323T0837Z             Ordinal date and UTC of day (basic)
%Y-%jT%RZ        => 2007-323T08:37Z           Ordinal date and UTC of day (extended)
%GW%V%uT%H%M%z   => 2007W471T0837-0600        Week date and local time and difference f