Hi there, If you want to show off just how good R handles dates+times, forward this. I showed some colleagues difftime today, and encountered something interesting: difftime(ISOdatetime(1936:1947+1,1,1, 0,0,0), ISOdatetime(1936:1947,1,1, 0,0,0)) which returns the values 366, 365, 365, 365, 365.958333, 365, 365.041667, 365, 366, 365, 365, 365 1940 is missing one hour! (1/24 = 0.041667) 1942 has one hour too much. I first thought of leap hours, and after reading about leap seconds, clock drift, timing attacks, GPS, random number generators and Turing machines, I thought of dailight saving time, and indeed, there were some issues in Germany back then. http://de.wikipedia.org/wiki/Sommerzeit#Deutschland http://www.horlogeparlante.com/history.html?city=2950159 R even covers all that - I'm once again amazed! Sys.getlocale() gives me German_Germany.1252, by the way. regards, Berry