Index: openacs-4/packages/xotcl-core/tcl/ical-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/ical-procs.tcl,v
diff -u -N -r1.16 -r1.17
--- openacs-4/packages/xotcl-core/tcl/ical-procs.tcl	19 Mar 2018 13:33:23 -0000	1.16
+++ openacs-4/packages/xotcl-core/tcl/ical-procs.tcl	20 Mar 2018 07:16:30 -0000	1.17
@@ -36,7 +36,8 @@
     clock format [clock scan $time] -format "%Y%m%dT%H%M%SZ" -gmt 1
   }
   ical proc tcl_time_to_local_day {time} {
-    VALUE=DATE:[:clock_to_local_day [clock scan $time]]
+    # https://tools.ietf.org/html/rfc5545#section-3.3.4
+    return "VALUE=DATE:[:clock_to_local_day [clock scan $time]]"
   }
   ical proc utc_to_clock {utc_time} {
     clock scan $utc_time -format "%Y%m%dT%H%M%SZ" -gmt 1
@@ -107,7 +108,7 @@
   }
 
   ::xo::ical::VCALITEM instproc tag {-tag -conv -value slot} {
-    ns_log notice "::xo::ical::VCALITEM tag [self args]"
+    #ns_log notice "::xo::ical::VCALITEM tag [self args]"
     if {![info exists tag]} {
       set tag [string toupper $slot]
     }
@@ -146,10 +147,9 @@
   }
 
   ::xo::ical::VCALITEM instproc start_end {} {
-    if {[:is_day_item]} {
+    if {${:is_day_item}} {
       append result \
-          [:tag -conv tcl_time_to_local_day dtstart] \
-          [:tag -conv tcl_time_to_local_day dtend]
+          "DTSTART;" [::xo::ical tcl_time_to_local_day ${:dtstart}] \r\n
     } else {
       append result \
           [:tag -conv tcl_time_to_utc dtstart] \
@@ -196,8 +196,7 @@
         [:tag -conv tcl_time_to_utc -value $tcl_creation_date created] \
         [:tag -conv tcl_time_to_utc -value $tcl_last_modified last-modified] \
         [:tag -conv tcl_time_to_utc -value $tcl_stamp dtstamp] \
-        [:tag -conv tcl_time_to_utc dtstart] \
-        [:tag -conv tcl_time_to_utc dtend] \
+        [:start_end] \
         [:tag -conv tcl_time_to_utc completed] \
         [:tag -conv tcl_time_to_utc percent-complete] \
         [:tag transp] \