clock patch

--- d:/SourceForge/tcl/library/clock.tcl	Fri Sep 11 14:30:27 2009
+++ d:/tcl8.6test/lib/tcl8.6/clock.tcl	Sat Oct 24 17:16:40 2009
@@ -3789,11 +3789,16 @@
     }
 
     # Fill in defaults for European or US DST rules
+    # US start time is the second Sunday in March
+    # EU start time is the last Sunday in March
+    # US end time is the first Sunday in November.
+    # EU end time is the last Sunday in October
 
     if {
 	[dict get $z startDayOfYear] eq {} && [dict get $z startMonth] eq {}
     } then {
-	if {($stdHours>=0) && ($stdHours<=12)} {
+	if {($stdSignum * $stdHours>=0) && ($stdSignum * $stdHours<=12)} {
+	    # EU
 	    dict set z startWeekOfMonth 5
 	    if {$stdHours>2} {
 		dict set z startHours 2
@@ -3801,6 +3806,7 @@
 		dict set z startHours [expr {$stdHours+1}]
 	    }
 	} else {
+	    # US
 	    dict set z startWeekOfMonth 2
 	    dict set z startHours 2
 	}
@@ -3812,7 +3818,8 @@
     if {
 	[dict get $z endDayOfYear] eq {} && [dict get $z endMonth] eq {}
     } then {
-	if {($stdHours>=0) && ($stdHours<=12)} {
+	if {($stdSignum * $stdHours>=0) && ($stdSignum * $stdHours<=12)} {
+	    # EU
 	    dict set z endMonth 10
 	    dict set z endWeekOfMonth 5
 	    if {$stdHours>2} {
@@ -3821,6 +3828,7 @@
 		dict set z endHours [expr {$stdHours+2}]
 	    }
 	} else {
+	    # US
 	    dict set z endMonth 11
 	    dict set z endWeekOfMonth 1
 	    dict set z endHours 2