diff --git a/Graphics/Rendering/Chart/Event.hs b/Graphics/Rendering/Chart/Event.hs
--- a/Graphics/Rendering/Chart/Event.hs
+++ b/Graphics/Rendering/Chart/Event.hs
@@ -21,7 +21,8 @@
 import Data.Accessor.Template
 import Control.Monad
 
-data Event t e = LongEvent t t e  -- ^ An event that has a beginning and an end
+data Event t e = LongEvent (t,Bool) (t,Bool) e  -- ^ An event that has a beginning and an end. 
+                                                --   True = "known explicitly", False = "implicit" (e.g. imposed by axis bounds)
                | PulseEvent t e   -- ^ A zero-length event
                deriving (Show)
 
@@ -86,7 +87,7 @@
       (Point x1 y1) = pmap (LMax,LMax)
       (cx,cy) = ((x0+x1)/2, (y0+y1)/2)
       drawEventFill (PulseEvent t e) = return ()
-      drawEventFill (LongEvent t1 t2 e) = do
+      drawEventFill (LongEvent (t1,_) (t2,_) e) = do
         let (Point x1 cy)  = pmap (LValue t1, LValue e)
         let (Point x2 cy') = pmap (LValue t2, LValue e) -- Assume cy' == cy (pmap is coordinate-wise)
         filledRect (plot_event_long_fillstyle_ p e) $ Rect
@@ -104,7 +105,7 @@
           moveTo (Point x (y - pulseHeight/2 - C.textExtentsHeight extents - C.textExtentsYbearing extents - 1))
           setLineStyle $ solidLine 2 (opaque black)
           c $ C.showText label
-      drawEventFrame (LongEvent t1 t2 e) = do
+      drawEventFrame (LongEvent (t1,_) (t2,_) e) = do
         let (Point x1 cy)  = pmap (LValue t1, LValue e)
         let (Point x2 cy') = pmap (LValue t2, LValue e) -- Assume cy' == cy (pmap is coordinate-wise)
         framedRect (plot_event_long_linestyle_ p e) $ Rect
@@ -114,7 +115,7 @@
 plotAllPointsEvent p = let (ts, es) = unzip (map decomp d) in (concat ts, es)
   where
     d = plot_event_data_ p
-    decomp (PulseEvent t     e) = ([t],     e)
-    decomp (LongEvent  t1 t2 e) = ([t1,t2], e)
+    decomp (PulseEvent t             e) = ([t],     e)
+    decomp (LongEvent  (t1,_) (t2,_) e) = ([t1,t2], e)
 
 $( deriveAccessors ''PlotEvent )
diff --git a/Tools/TimePlot.hs b/Tools/TimePlot.hs
--- a/Tools/TimePlot.hs
+++ b/Tools/TimePlot.hs
@@ -342,7 +342,7 @@
       KindDots            -> withAnyOrdinate $ plotTrackDots      name es
       KindSum       bs ss -> withAnyOrdinate $ plotTrackSum       name es bs ss
       KindCumSum    ss    -> withAnyOrdinate $ plotTrackCumSum    name es ss
-      KindDuration  sk    -> plotWithKind       name sk (edges2durations (edges es) minTime maxTime)
+      KindDuration  sk    -> plotWithKind       name sk (edges2durations (edges es) minTime maxTime name)
       KindWithin    _ _   -> error "KindDuration should not be plotted"
       KindNone            -> error "KindNone should not be plotted"
 
@@ -540,8 +540,10 @@
         layout1_grid_last ^= True $
         defaultLayout1
 
-edges2durations :: forall t. (Ord t, HasDelta t) => [(t,S.ByteString,Edge)] -> t -> t -> [(t,InEvent)]
-edges2durations tes minTime maxTime = [(t2, InValue track $ toSeconds (t2 `sub` t1) (undefined::t)) | (track,LongEvent t1 t2 _) <- edges2events tes minTime maxTime]
+edges2durations :: forall t. (Ord t, HasDelta t) => [(t,S.ByteString,Edge)] -> t -> t -> S.ByteString -> [(t,InEvent)]
+edges2durations tes minTime maxTime commonTrack = 
+    [(t2, InValue commonTrack $ toSeconds (t2 `sub` t1) (undefined::t)) 
+    | (track, LongEvent (t1,True) (t2,True) _) <- edges2events tes minTime maxTime]
 
 edges2events :: (Ord t) => [(t,S.ByteString,Edge)] -> t -> t -> [(S.ByteString,Event t Status)]
 edges2events tes minTime maxTime = snd $ RWS.execRWS (mapM_ step tes >> flush) () M.empty 
@@ -559,17 +561,17 @@
 
     step (t,s,Pulse st) = RWS.tell [(s, PulseEvent t st)]
     step (t,s,SetTo st) = trackCase s (putTrack s (t, 1, st))
-                                      (\t0 n st0 -> RWS.tell [(s, LongEvent t0 t st0)] >> 
+                                      (\t0 n st0 -> RWS.tell [(s, LongEvent (t0,True) (t,True) st0)] >> 
                                                     putTrack s (t, n, st))
     step (t,s,Rise)     = trackCase s (putTrack s (t, 1, emptyStatus)) 
                                       (\t0 n st -> putTrack s (t, n+1, st))
     step (t,s,Fall)     = do
       (t0, numActive, st) <- getTrack s
       case numActive of
-        1 -> RWS.tell [(s, LongEvent t0 t st)] >> killTrack s
+        1 -> RWS.tell [(s, LongEvent (t0,True) (t,True) st)] >> killTrack s
         n -> putTrack s (t0, max 0 (n-1), st)
 
-    flush = RWS.get >>= mapM_ (\(s, (t0,_,st)) -> RWS.tell [(s, LongEvent t0 maxTime st)]) . M.toList
+    flush = RWS.get >>= mapM_ (\(s, (t0,_,st)) -> RWS.tell [(s, LongEvent (t0,True) (maxTime,False) st)]) . M.toList
 
 edges2bins :: forall t. (Ord t,HasDelta t,Show t) => Delta t -> t -> t -> [(t,S.ByteString,Edge)] -> [((t,t), [(S.ByteString,Double)])]
 edges2bins binSize minTime maxTime es = snd $ RWS.execRWS (mapM_ step es >> flush) () (M.empty, iterate (add binSize) minTime)
diff --git a/timeplot.cabal b/timeplot.cabal
--- a/timeplot.cabal
+++ b/timeplot.cabal
@@ -1,5 +1,5 @@
 name: timeplot
-version: 0.3.2
+version: 0.3.3
 cabal-version: >=1.6
 build-type: Simple
 license: BSD3