diff --git a/common/ShowCode.hs b/common/ShowCode.hs
index 74ad611..f76d4ef 100644
--- a/common/ShowCode.hs
+++ b/common/ShowCode.hs
@@ -255,11 +255,9 @@ instance ShowOccam A.Type where
       = tell [shared, "CHAN", direction, " "] >> showOccamM t
     where
       shared
-          = case (A.caWritingShared ca, A.caReadingShared ca) of
-              (A.Unshared, A.Unshared) -> ""
-              (A.Shared, A.Unshared) -> "SHARED! "
-              (A.Unshared, A.Shared) -> "SHARED? "
-              (A.Shared, A.Shared) -> "SHARED "
+          = case ca of
+              A.Unshared -> ""
+              A.Shared -> "SHARED "
       direction
           = case dir of
               A.DirInput -> "?"
@@ -303,8 +301,8 @@ instance ShowRain A.Type where
       ao b = if b == A.Shared then "any" else "one"  
   showRainM (A.ChanEnd dir attr t) 
     = case dir of
-        A.DirInput -> tell [if A.caReadingShared attr == A.Shared then "shared" else "", " ?"] >> showRainM t
-        A.DirOutput -> tell [if A.caWritingShared attr == A.Shared then "shared" else "", " !"] >> showRainM t
+        A.DirInput -> tell [if attr == A.Shared then "shared" else "", " ?"] >> showRainM t
+        A.DirOutput -> tell [if attr == A.Shared then "shared" else "", " !"] >> showRainM t
     where
       ao :: Bool -> String
       ao b = if b then "any" else "one"  
diff --git a/common/Types.hs b/common/Types.hs
index b529c4b..b0e97c0 100644
--- a/common/Types.hs
+++ b/common/Types.hs
@@ -29,7 +29,7 @@ module Types
       mulExprs, divExprs
     , addDimensions, applyDimension, removeFixedDimensions, trivialSubscriptType, subscriptType, unsubscriptType
     , applyDirection
-    , recordFields, recordAttr, protocolItems
+    , recordFields, recordAttr, protocolItems, dirAttr
 
     , leastGeneralSharedTypeRain
     
@@ -133,6 +133,9 @@ recordAttr m (A.Record rec)
             _ -> dieP m "not record type"
 recordAttr m _ = dieP m "not record type"
 
+dirAttr :: A.Direction -> A.ChanAttributes -> A.ShareMode
+dirAttr A.DirInput = A.caReadingShared
+dirAttr A.DirOutput = A.caWritingShared
 
 -- | Get the type of a record field.
 typeOfRecordField :: (CSMR m, Die m) => Meta -> A.Type -> A.Name -> m A.Type
@@ -228,14 +231,14 @@ typeOfVariable (A.DirectedVariable m dir v)
              if dir == dir'
                then return t
                else dieP m $ "Attempted to reverse direction of a channel-end"
-           A.Chan attr innerT -> return $ A.ChanEnd dir attr innerT
+           A.Chan attr innerT -> return $ A.ChanEnd dir (dirAttr dir attr) innerT
            A.Array ds (A.Chan attr innerT)
-             -> return $ A.Array ds (A.ChanEnd dir attr innerT)
+             -> return $ A.Array ds (A.ChanEnd dir (dirAttr dir attr) innerT)
            A.Array _ (A.ChanEnd dir' _ _) ->
              if dir == dir'
                then return t
                else dieP m $ "Attempted to reverse direction of a channel-end"
-           A.Infer -> return $ A.ChanEnd dir (A.ChanAttributes A.Unshared A.Unshared) A.Infer
+           A.Infer -> return $ A.ChanEnd dir A.Unshared A.Infer
            _ -> diePC m $ formatCode "Direction specified on non-channel variable of type: %" t
 
 -- | Get the abbreviation mode of a variable.
@@ -415,7 +418,7 @@ applyDirection :: Die m => Meta -> A.Direction -> A.Type -> m A.Type
 applyDirection m dir (A.Array ds t)
     = applyDirection m dir t >>* A.Array ds
 applyDirection m dir (A.Chan ca t)
-    = return $ A.ChanEnd dir ca t
+    = return $ A.ChanEnd dir (dirAttr dir ca) t
 applyDirection m _ t
     = dieP m "Direction specified on non-channel type"
 
diff --git a/data/AST.hs b/data/AST.hs
index dd29174..828fad1 100644
--- a/data/AST.hs
+++ b/data/AST.hs
@@ -133,7 +133,7 @@ data Type =
   -- | A channel of the specified type.
   | Chan ChanAttributes Type
   -- | A channel end of the specified type.
-  | ChanEnd Direction ChanAttributes Type
+  | ChanEnd Direction ShareMode Type
   -- | A counted input or output.
   -- The first type is that of the count; the second is that of the array.
   -- (For example, @INT::[]BYTE@ would be @A.Counted A.Int (A.Array ...)@).
diff --git a/frontends/OccamTypes.hs b/frontends/OccamTypes.hs
index 4d99e5c..41b4a42 100644
--- a/frontends/OccamTypes.hs
+++ b/frontends/OccamTypes.hs
@@ -428,14 +428,13 @@ checkChannel wantDir c
     =  do -- Check it's a channel.
           t <- astTypeOf c >>= resolveUserType m
           case t of
-            A.ChanEnd dir (A.ChanAttributes ws rs) innerT ->
+            A.ChanEnd dir sh innerT ->
                do -- Check the direction is appropriate 
                   when (wantDir /= dir) $ dieP m $ "Channel directions do not match"
                   -- Check it's not shared in the direction we're using.
-                  case (ws, rs, wantDir) of
-                    (A.Unshared, _, A.DirOutput) -> ok
-                    (_, A.Unshared, A.DirInput) -> ok
-                    _ -> dieP m $ "Shared channel must be claimed before use"
+                  case sh of
+                    A.Unshared -> ok
+                    A.Shared -> dieP m $ "Shared channel must be claimed before use"
 
                   return innerT
             _ -> diePC m $ formatCode ("Expected channel " ++ exp ++ "; found %") t
@@ -851,7 +850,7 @@ inferTypes = occamOnlyPass "Infer types"
                          do dirs <- ask >>= (lift . findDir n)
                             case nub dirs of
                               [dir] ->
-                                do let tEnd = A.ChanEnd dir attr innerT
+                                do let tEnd = A.ChanEnd dir (dirAttr dir attr) innerT
                                    return (tEnd, A.DirectedVariable m dir v')
                               _ -> return (vt, v') -- no direction, or two
                     (A.Infer, _) -> return (vt, v')
@@ -870,7 +869,7 @@ inferTypes = occamOnlyPass "Infer types"
                          do dirs <- ask >>= (lift . findDir n)
                             case nub dirs of
                               [dir] ->
-                                do let tEnd = A.ChanEnd dir attr innerT
+                                do let tEnd = A.ChanEnd dir (dirAttr dir attr) innerT
                                    return (tEnd, A.DirectedVariable m dir v')
                               _ -> return (t', v') -- no direction, or two
                     _ -> return (t', v')
@@ -904,7 +903,7 @@ inferTypes = occamOnlyPass "Infer types"
                     A.Array ds (A.Chan attr innerT) -> do
                       dirs <- ask >>= (lift . findDir n)
                       case nub dirs of
-                        [dir] -> return (A.Array ds $ A.ChanEnd dir attr innerT
+                        [dir] -> return (A.Array ds $ A.ChanEnd dir (dirAttr dir attr) innerT
                                         ,A.DirectedVariable m dir)
                         _ -> return (t'', id)
                     _ -> return (t'', id)
@@ -931,7 +930,7 @@ inferTypes = occamOnlyPass "Infer types"
                          do dirs <- findDir n body
                             case nub dirs of
                               [dir] ->
-                                do let t' = A.ChanEnd dir attr innerT
+                                do let t' = A.ChanEnd dir (dirAttr dir attr) innerT
                                        f' = A.Formal am t' n
                                    modifyName n (\nd -> nd {A.ndSpecType =
                                      A.Declaration m t'})
diff --git a/frontends/ParseOccam.hs b/frontends/ParseOccam.hs
index 0cbde60..5438a25 100644
--- a/frontends/ParseOccam.hs
+++ b/frontends/ParseOccam.hs
@@ -1182,7 +1182,7 @@ definition
                       dir <- direction
                       sColon
                       eol
-                      return (n, A.ChanEnd dir (A.ChanAttributes A.Unshared A.Unshared) t)
+                      return (n, A.ChanEnd dir A.Unshared t)
 
 retypesAbbrev :: OccParser NameSpec
 retypesAbbrev
diff --git a/frontends/ParseRain.hs b/frontends/ParseRain.hs
index f42c0c1..706b49a 100644
--- a/frontends/ParseRain.hs
+++ b/frontends/ParseRain.hs
@@ -168,8 +168,8 @@ dataType
     <|> do {reserved "sint64" ; return A.Int64}    
     <|> do {reserved "time" ; return A.Time}
     <|> do {sChannel ; inner <- dataType ; return $ A.Chan (A.ChanAttributes {A.caWritingShared = A.Unshared, A.caReadingShared = A.Unshared}) inner}
-    <|> do {sIn ; inner <- dataType ; return $ A.ChanEnd A.DirInput (A.ChanAttributes {A.caWritingShared = A.Unshared, A.caReadingShared = A.Unshared}) inner}
-    <|> do {sOut ; inner <- dataType ; return $ A.ChanEnd A.DirOutput (A.ChanAttributes {A.caWritingShared = A.Unshared, A.caReadingShared = A.Unshared}) inner}
+    <|> do {sIn ; inner <- dataType ; return $ A.ChanEnd A.DirInput A.Unshared inner}
+    <|> do {sOut ; inner <- dataType ; return $ A.ChanEnd A.DirOutput A.Unshared inner}
     <|> do {sLeftQ ; inner <- dataType ; sRightQ ; return $ A.List inner}
     <|> do {(m,n) <- identifier ; return $ A.UserDataType A.Name {A.nameMeta = m, A.nameName = n}}
     <?> "data type"
diff --git a/frontends/RainTypes.hs b/frontends/RainTypes.hs
index 0a851cc..e076acc 100644
--- a/frontends/RainTypes.hs
+++ b/frontends/RainTypes.hs
@@ -282,8 +282,7 @@ markCommTypes = checkDepthM2 checkInputOutput checkAltInput
   where
     checkInput :: A.Variable -> A.Variable -> Meta -> a -> RainTypeM ()
     checkInput chanVar destVar m p
-      = astTypeOf destVar >>= markUnify chanVar . A.ChanEnd A.DirInput (A.ChanAttributes
-        A.Unshared A.Unshared)
+      = astTypeOf destVar >>= markUnify chanVar . A.ChanEnd A.DirInput A.Unshared
 
     checkWait :: RainTypeCheck A.InputMode
     checkWait (A.InputTimerFor m exp) = markUnify A.Time exp
@@ -298,8 +297,7 @@ markCommTypes = checkDepthM2 checkInputOutput checkAltInput
     checkInputOutput (A.Input _ _ im@(A.InputTimerAfter {})) = checkWait im
     checkInputOutput (A.Input _ _ im@(A.InputTimerRead {})) = checkWait im
     checkInputOutput p@(A.Output m chanVar [A.OutExpression m' srcExp])
-      = astTypeOf srcExp >>= markUnify chanVar . A.ChanEnd A.DirOutput (A.ChanAttributes
-        A.Unshared A.Unshared)
+      = astTypeOf srcExp >>= markUnify chanVar . A.ChanEnd A.DirOutput A.Unshared
     checkInputOutput _ = return ()
 
     checkAltInput :: RainTypeCheck A.Alternative
diff --git a/transformations/SimplifyExprs.hs b/transformations/SimplifyExprs.hs
index 9379714..b84c02d 100644
--- a/transformations/SimplifyExprs.hs
+++ b/transformations/SimplifyExprs.hs
@@ -460,7 +460,7 @@ pullUp pullUpArraysInsideRecords = pass "Pull up definitions"
                             n) v) innerV (replicate i $ makeConstant m 0)
                         | (d, i) <- zip ds [0..]]
                   spec@(A.Specification _ n _) <- makeNonceIs "dir_array" m
-                    (A.Array ds' $ A.ChanEnd dir attr innerT) A.Abbrev v
+                    (A.Array ds' $ A.ChanEnd dir (dirAttr dir attr) innerT) A.Abbrev v
                   addPulled $ (m, Left spec)
                   return $ A.Variable m n
              _ -> descend v