Here's another specific reference, from http://www.magnet.ch/serendipity/hermetic/cal_stud/cal_art.htm#Proleptic # Every date recorded in history prior to October 15, 1582 (Gregorian), # such as the coronation of Charlemagne as Holy Roman Emperor on # Christmas day in the year 800, is a date in the Julian Calendar, since # on those dates the Gregorian Calendar had not yet been invented. # We can, however, identify particular days prior to October 15, 1582 # (Gregorian), by means of dates in the Gregorian Calendar simply by # projecting the Gregorian dating system back beyond the time of its # implementation. A calendar obtained by extension earlier in time # than its invention or implementation is called the "proleptic" # version of the calendar, and thus we obtain the Proleptic Gregorian # Calendar. The Julian Calendar also can be extended backward as the # Proleptic Julian Calendar. # For example, even though the Gregorian Calendar was implemented on # October 15, 1582 (Gregorian) we can still say that the date of the # day one year before was October 15, 1581 (Gregorian), even though # people alive on that day would have said that the date was October 5, # 1581 (the Julian date at that time). As another example, the date # of the coronation of Charlemagne, December 25, 800, in the Julian # Calendar, was December 29, 800, in the Proleptic Gregorian Calendar. -- John Cowan http://www.ccil.org/~cowan cowan@ccil.org You tollerday donsk? N. You tolkatiff scowegian? Nn. You spigotty anglease? Nnn. You phonio saxo? Nnnn. Clear all so! 'Tis a Jute.... (Finnegans Wake 16.5)