+ Gr_Unknown, ///< no data for this country or it's too uncertain to use
+ Gr_Standard, ///< on the day 0 of Gregorian calendar: 15 Oct 1582
+
+ Gr_Alaska, ///< Oct 1867 when Alaska became part of the USA
+ Gr_Albania, ///< Dec 1912
+
+ Gr_Austria = Gr_Unknown, ///< Different regions on different dates
+ Gr_Austria_Brixen, ///< 5 Oct 1583 -> 16 Oct 1583
+ Gr_Austria_Salzburg = Gr_Austria_Brixen,
+ Gr_Austria_Tyrol = Gr_Austria_Brixen,
+ Gr_Austria_Carinthia, ///< 14 Dec 1583 -> 25 Dec 1583
+ Gr_Austria_Styria = Gr_Austria_Carinthia,
+
+ Gr_Belgium, ///< Then part of the Netherlands
+
+ Gr_Bulgaria = Gr_Unknown, ///< Unknown precisely (from 1915 to 1920)
+ Gr_Bulgaria_1, ///< 18 Mar 1916 -> 1 Apr 1916
+ Gr_Bulgaria_2, ///< 31 Mar 1916 -> 14 Apr 1916
+ Gr_Bulgaria_3, ///< 3 Sep 1920 -> 17 Sep 1920
+
+ Gr_Canada = Gr_Unknown, ///< Different regions followed the changes in
+ ///< Great Britain or France
+
+ Gr_China = Gr_Unknown, ///< Different authorities say:
+ Gr_China_1, ///< 18 Dec 1911 -> 1 Jan 1912
+ Gr_China_2, ///< 18 Dec 1928 -> 1 Jan 1929
+
+ Gr_Czechoslovakia, ///< (Bohemia and Moravia) 6 Jan 1584 -> 17 Jan 1584
+ Gr_Denmark, ///< (including Norway) 18 Feb 1700 -> 1 Mar 1700
+ Gr_Egypt, ///< 1875
+ Gr_Estonia, ///< 1918
+ Gr_Finland, ///< Then part of Sweden
+
+ Gr_France, ///< 9 Dec 1582 -> 20 Dec 1582
+ Gr_France_Alsace, ///< 4 Feb 1682 -> 16 Feb 1682
+ Gr_France_Lorraine, ///< 16 Feb 1760 -> 28 Feb 1760
+ Gr_France_Strasbourg, ///< February 1682
+
+ Gr_Germany = Gr_Unknown, ///< Different states on different dates:
+ Gr_Germany_Catholic, ///< 1583-1585 (we take 1584)
+ Gr_Germany_Prussia, ///< 22 Aug 1610 -> 2 Sep 1610
+ Gr_Germany_Protestant, ///< 18 Feb 1700 -> 1 Mar 1700
+
+ Gr_GreatBritain, ///< 2 Sep 1752 -> 14 Sep 1752 (use 'cal(1)')
+
+ Gr_Greece, ///< 9 Mar 1924 -> 23 Mar 1924
+ Gr_Hungary, ///< 21 Oct 1587 -> 1 Nov 1587
+ Gr_Ireland = Gr_GreatBritain,
+ Gr_Italy = Gr_Standard,
+
+ Gr_Japan = Gr_Unknown, ///< Different authorities say:
+ Gr_Japan_1, ///< 19 Dec 1872 -> 1 Jan 1873
+ Gr_Japan_2, ///< 19 Dec 1892 -> 1 Jan 1893
+ Gr_Japan_3, ///< 18 Dec 1918 -> 1 Jan 1919
+
+ Gr_Latvia, ///< 1915-1918 (we take 1915)
+ Gr_Lithuania, ///< 1915
+ Gr_Luxemburg, ///< 14 Dec 1582 -> 25 Dec 1582
+ Gr_Netherlands = Gr_Belgium, ///< (including Belgium) 1 Jan 1583
+
+ /**
+ Special case of Groningen.
+
+ The Gregorian calendar was introduced twice in Groningen, first
+ time 28 Feb 1583 was followed by 11 Mar 1583, then it has gone back
+ to Julian in the summer of 1584 and then 13 Dec 1700 was followed
+ by 12 Jan 1701 -- which is the date we take into account here.
+ */
+ Gr_Netherlands_Groningen, ///< 13 Dec 1700 -> 12 Jan 1701
+ Gr_Netherlands_Gelderland, ///< 30 Jun 1700 -> 12 Jul 1700
+ Gr_Netherlands_Utrecht, ///< (and Overijssel) 30 Nov 1700->12 Dec 1700
+ Gr_Netherlands_Friesland, ///< (and Drenthe) 31 Dec 1700 -> 12 Jan 1701
+
+ Gr_Norway = Gr_Denmark, ///< Then part of Denmark
+ Gr_Poland = Gr_Standard,
+ Gr_Portugal = Gr_Standard,
+ Gr_Romania, ///< 31 Mar 1919 -> 14 Apr 1919
+ Gr_Russia, ///< 31 Jan 1918 -> 14 Feb 1918
+ Gr_Scotland = Gr_GreatBritain,
+ Gr_Spain = Gr_Standard,
+
+ /**
+ Special case of Sweden.
+
+ Sweden has a curious history. Sweden decided to make a gradual
+ change from the Julian to the Gregorian calendar. By dropping every
+ leap year from 1700 through 1740 the eleven superfluous days would
+ be omitted and from 1 Mar 1740 they would be in sync with the
+ Gregorian calendar. (But in the meantime they would be in sync with
+ nobody!)
+
+ So 1700 (which should have been a leap year in the Julian calendar)
+ was not a leap year in Sweden. However, by mistake 1704 and 1708
+ became leap years. This left Sweden out of synchronisation with
+ both the Julian and the Gregorian world, so they decided to go back
+ to the Julian calendar. In order to do this, they inserted an extra
+ day in 1712, making that year a double leap year! So in 1712,
+ February had 30 days in Sweden.
+
+ Later, in 1753, Sweden changed to the Gregorian calendar by
+ dropping 11 days like everyone else and this is what we use here.
+ */
+ Gr_Sweden = Gr_Finland, ///< 17 Feb 1753 -> 1 Mar 1753
+
+ Gr_Switzerland = Gr_Unknown,///< Different cantons used different dates
+ Gr_Switzerland_Catholic, ///< 1583, 1584 or 1597 (we take 1584)
+ Gr_Switzerland_Protestant, ///< 31 Dec 1700 -> 12 Jan 1701
+
+ Gr_Turkey, ///< 1 Jan 1927
+ Gr_USA = Gr_GreatBritain,
+ Gr_Wales = Gr_GreatBritain,
+ Gr_Yugoslavia ///< 1919