This function uses the first argument as a formatting string. This string may contain the following character strings:
YEAR four digit year
YY two digit year
MON three letter abbreviation of the month name
MM month
0M month with leading zero if needed
*MONTH-NAME* name of the month
DD day of the month
0D day of the month with leading zero if needed
WD week day on a single digit starting with sunday=0
WEEKDAY-NAME the name of the weekday
WDN three letter abbreviation fo the week day name
HH hours (24 hours notation)
0H hours with leading zero if needed (24 hours notation)
hh hours (12 hours notation)
0h hours with leading zero if needed (12 hours notation)
mm minutes
0m minutes with leading zero if needed
am
pm is am or pm
Any other character in the format string will get into the result verbatim.