X-Git-Url: http://git.kpe.io/?p=kmrcl.git;a=blobdiff_plain;f=datetime.lisp;h=4a4dbe2e321feae2789864b0d657c82759a9a1c6;hp=771d75ad794f3e7cc06331bdc7beecb7449ab5c4;hb=98d7b650aa611a0de537ace581cde47c66071af3;hpb=37c6b4baf974335c53828b760ed023f37098cf19

diff --git a/datetime.lisp b/datetime.lisp
index 771d75a..4a4dbe2 100644
--- a/datetime.lisp
+++ b/datetime.lisp
@@ -68,3 +68,36 @@
     (t
      (format t "~,2F ~A" val unit))))
 
+
+;;;; Daylight Saving Time calculations 
+
+;; Daylight Saving Time begins for most of the United States at 2
+;; a.m. on the first Sunday of April. Time reverts to standard time at
+;; 2 a.m. on the last Sunday of October. In the U.S., each time zone
+;; switches at a different time.
+
+;; In the European Union, Summer Time begins and ends at 1 am
+;; Universal Time (Greenwich Mean Time). It starts the last Sunday in
+;; March, and ends the last Sunday in October. In the EU, all time
+;; zones change at the same moment.
+
+;; Spring forward, Fall back
+;; During DST, clocks are turned forward an hour, effectively moving
+;; an hour of daylight from the morning to the evening.
+
+;; United States                  European Union
+
+;; Year  DST Begins DST Ends     Summertime     Summertime
+;;       at 2 a.m.  at 2 a.m.    period begins  period ends
+;;                               at 1 a.m. UT   at 1 a.m. UT
+;; ----------------------------------------------------------
+;; 2000  April 2   October 29    March 26       October 29
+;; 2001  April 1   October 28    March 25       October 28
+;; 2002  April 7   October 27    March 31       October 27
+;; 2003  April 6   October 26    March 30       October 26
+;; 2004  April 4   October 31    March 28       October 31
+;; 2005  April 3   October 30    March 27       October 30
+;; 2006  April 2   October 29    March 26       October 29
+;; 2007  April 1   October 28    March 25       October 28
+;; 2008  April 6   October 26    March 30       October 26
+