Formats a time value (or date) according to the format string. The format string may contain placeholders. The first argument is the format string the second argument is the time value to convert. If the second argument is missing or it is undef then the local time is converted.
If the time value is presented it has to be the number of seconds elapsed since January 1, 1970. This is the usual time stamp value generally used under UNIX.
If the second argument is a negativevalue then this is treated relative to the current time point. For example
print FormatDate("YEAR MON DD HH:mm:ss", -60)
will print out the time that was one minute ago.