St. Martin's Day calendar. It remains popular today, especially among young people and the rural population. Martinmas celebrates the end of the agrarian year and the beginning of the winter period. Among Estonians, Martinmas also marks the end of the period of All Souls, as well as the autumn period in the Estonian popular calendar when the souls of ancestors were worshiped, a period that lasted from November 1 to Martinmas (November 11). On this day children disguise themselves as men and go from door to door, singing songs and telling jokes to receive sweets. In Southern Estonia, November is called "Märtekuu" after
Key date Key date In coin collecting, a key date refers to a date (or date and mint mark combination) of a given coin series or set that is harder to obtain than other dates in the series. The next level of difficult to obtain coins in series are often referred to as semi-key dates or simply semi-keys. For example, the 1909-S VDB is the key date in the Lincoln cent series. The 1914-D and 1931-S are considered semi-keys. In the United Kingdom £1 coins from 1988 are considered key date coins. What makes a coin a "key" is somewhat more complicated