Review the list of modifiers.
The time string can be followed by zero or modifiers that alter the date or alter the interpretation of the date. The available modifiers are:
The “start of” modifiers (7 – 9) shift the date backward to the beginning of the current month, year, or day.
The “weekday” (10) modifier advances the date forward to the next date where the weekday number is N: Sunday is 0, Monday is 1, and so on.
The unixepoch modifier (11) works only if it immediately follows a time string in the DDDD.DDDDD format. This modifier causes the DDDD.DDDDD to be interpreted not as a Julian day number as it normally would be, but as the number of seconds since 1970. This modifier allows UNIX-based times to be easily converted to Julian day numbers.
The localtime modifier (12) adjusts the previous time string so that it displays the correct local time. utc undoes this.