Why does DateTimeInfo.MonthNames return a 13 member? [duplicate]

Question

Possible Duplicate:
GetMonthName: Valid values are between 1 and 13, inclusive. Why?

The following code:

DateTimeFormatInfo datetimeinfo = new CultureInfo("en-GB", false).DateTimeFormat;
string[] months = datetimeinfo.MonthNames;

returns 13 members, with 0 being January and 13 being an empty string.

Why is this?

It's no big deal as I can just remove the last member, but I just wondered if there was a point to it.

Answer 1

Some calendars, notably the Hebrew, can have 13 months. This tends to be in lunisolar calendars which use Lunar months, and then add an extra month every few years to avoid the start of the year changing too much from the solar year.