Year zero
Year zero does not exist in the anno Domini system usually used to number years in the Gregorian calendar and in its predecessor, the Julian calendar. In this system, the year is followed by . However, there is a year zero in astronomical year numbering (where it coincides with the Julian year ) and in ISO 8601:2004 (where it coincides with the Gregorian year ) as well as in all Buddhist and Hindu calendars.
Date and time notation in Serbia
Years can be written either with four or two digits, and in the latter case, century is usually replaced with an apostrophe (31. 12. ’06.). Leading zero is rarely used, and in those cases which are considered bad practice, only with months (however it is also optional for the days) (6. 05. 2006.). When literal names of the months are used they are not capitalized, and the four-digit format for the year is always used (31. December 2006). Yet another alternative is to use Roman numerals to indicate the month. In this case a dot is omitted (31. XII 2006).