diff --git a/src/GF/Canon/PrintGFC.hs b/src/GF/Canon/PrintGFC.hs
index ef41055ed..11b4729c0 100644
--- a/src/GF/Canon/PrintGFC.hs
+++ b/src/GF/Canon/PrintGFC.hs
@@ -16,6 +16,22 @@ type Doc = [ShowS] -> [ShowS]
 doc :: ShowS -> Doc
 doc = (:)
 
+docs :: ShowS -> Doc
+docs x y = concatD [spc, doc x, spc ] y
+
+spc = doc (showString "&")
+
+render :: Doc -> String
+render d = rend 0 (map ($ "") $ d []) "" where
+  rend i ss = case ss of
+    "*"    :ts -> realnew . rend i ts --H
+    "&":"&":ts -> showChar ' ' . rend i ts --H
+    "&"    :ts -> rend i ts --H
+    t      :ts -> showString t . rend i ts
+    _          -> id
+  realnew = showChar '\n' --H
+
+{-
 render :: Doc -> String
 render d = rend 0 (map ($ "") $ d []) "" where
   rend i ss = case ss of
@@ -26,20 +42,24 @@ render d = rend 0 (map ($ "") $ d []) "" where
     "["      :ts -> showChar '[' . rend i ts
     "("      :ts -> showChar '(' . rend i ts
     "{"      :ts -> showChar '{' . new (i+1) . rend (i+1) ts
-    "}" : ";":ts -> new (i-1) . space "}" . showChar ';' . new (i-1) . rend (i-1) ts
+    "}" : ";":ts -> new (i-1) . showChar '}' . showChar ';' . new (i-1) . rend (i-1) ts
     "}"      :ts -> new (i-1) . showChar '}' . new (i-1) . rend (i-1) ts
     ";"      :ts -> showChar ';' . new i . rend i ts
-    t  : "," :ts -> showString t . space "," . rend i ts
+    t  : "@" :ts -> showString t . showChar '@' . rend i ts
+    t  : "," :ts -> showString t . showChar ',' . rend i ts
     t  : ")" :ts -> showString t . showChar ')' . rend i ts
     t  : "]" :ts -> showString t . showChar ']' . rend i ts
-    t  : ">" :ts -> showString t . showString ">" . rend i ts --H
-    t  : "." :ts -> showString t . showString "." . rend i ts --H
+    t  : ">" :ts -> showString t . showChar '>' . rend i ts --H
+    t  : "." :ts -> showString t . showChar '.' . rend i ts --H
+    t@"=>"   :ts -> showString t . rend i ts --H
+    t@"->"   :ts -> showString t . rend i ts --H
     t        :ts -> realspace t . rend i ts --H
     _            -> id
   space t = showString t . showChar ' ' -- H
   realspace t = showString t . (\s -> if null s then "" else (' ':s)) -- H
   new i s   = s  -- H
   realnew = showChar '\n' --H
+-}
 
 parenth :: Doc -> Doc
 parenth ss = doc (showChar '(') . ss . doc (showChar ')')
@@ -79,14 +99,14 @@ prPrec i j = if j<i then parenth else id
 
 
 instance Print Integer where
-  prt _ x = doc (shows x)
+  prt _ x = docs (shows x)
 
 
 instance Print Double where
-  prt _ x = doc (shows x)
+  prt _ x = docs (shows x)
 
 instance Print Ident where
-  prt _ i = doc (showString $ prIdent i) -- H
+  prt _ i = docs (showString $ prIdent i) -- H
   prtList es = case es of
    [] -> (concatD [])
    [x] -> (concatD [prt 0 x])
@@ -94,13 +114,13 @@ instance Print Ident where
 
 instance Print Canon where
   prt i e = case e of
-   MGr ids id modules -> prPrec i 0 (concatD [doc (showString "grammar") , prt 0 ids , doc (showString "of") , prt 0 id , doc (showString ";") , prt 0 modules])
+   MGr ids id modules -> prPrec i 0 (concatD [spc, doc (showString "grammar") , spc, prt 0 ids , spc , doc (showString "of") , spc, prt 0 id , doc (showString ";") , prt 0 modules])
    Gr modules -> prPrec i 0 (concatD [prt 0 modules])
 
 
 instance Print Line where
   prt i e = case e of
-   LMulti ids id -> prPrec i 0 (concatD [doc (showString "grammar") , prt 0 ids , doc (showString "of") , prt 0 id , doc (showString ";")])
+   LMulti ids id -> prPrec i 0 (concatD [spc, doc (showString "grammar") , spc, prt 0 ids , spc, doc (showString "of") , spc, prt 0 id , doc (showString ";")])
    LHeader modtype extend open -> prPrec i 0 (concatD [prt 0 modtype , doc (showString "=") , prt 0 extend , prt 0 open , doc (showString "{")])
    LFlag flag -> prPrec i 0 (concatD [prt 0 flag , doc (showString ";")])
    LDef def -> prPrec i 0 (concatD [prt 0 def , doc (showString ";")])
@@ -117,10 +137,10 @@ instance Print Module where
 
 instance Print ModType where
   prt i e = case e of
-   MTAbs id -> prPrec i 0 (concatD [doc (showString "abstract") , prt 0 id])
-   MTCnc id0 id -> prPrec i 0 (concatD [doc (showString "concrete") , prt 0 id0 , doc (showString "of") , prt 0 id])
-   MTRes id -> prPrec i 0 (concatD [doc (showString "resource") , prt 0 id])
-   MTTrans id0 id1 id -> prPrec i 0 (concatD [doc (showString "transfer") , prt 0 id0 , doc (showString ":") , prt 0 id1 , doc (showString "->") , prt 0 id])
+   MTAbs id -> prPrec i 0 (concatD [spc, doc (showString "abstract") , spc , prt 0 id])
+   MTCnc id0 id -> prPrec i 0 (concatD [spc, doc (showString "concrete") , spc, prt 0 id0 , spc, doc (showString "of") , spc, prt 0 id])
+   MTRes id -> prPrec i 0 (concatD [spc, doc (showString "resource") , spc, prt 0 id])
+   MTTrans id0 id1 id -> prPrec i 0 (concatD [spc, doc (showString "transfer") , spc, prt 0 id0 , doc (showString ":") , prt 0 id1 , doc (showString "->") , prt 0 id])
 
 
 instance Print Extend where
@@ -131,13 +151,13 @@ instance Print Extend where
 
 instance Print Open where
   prt i e = case e of
-   Opens ids -> prPrec i 0 (concatD [doc (showString "open") , prt 0 ids , doc (showString "in")])
+   Opens ids -> prPrec i 0 (concatD [spc, doc (showString "open") , spc, prt 0 ids , docs (showString "in")])
    NoOpens  -> prPrec i 0 (concatD [])
 
 
 instance Print Flag where
   prt i e = case e of
-   Flg id0 id -> prPrec i 0 (concatD [doc (showString "flags") , prt 0 id0 , doc (showString "=") , prt 0 id])
+   Flg id0 id -> prPrec i 0 (concatD [spc, doc (showString "flags") , spc, prt 0 id0 , doc (showString "=") , prt 0 id])
 
   prtList es = case es of
    [] -> (concatD [])
@@ -145,18 +165,18 @@ instance Print Flag where
 
 instance Print Def where
   prt i e = case e of
-   AbsDCat id decls cidents -> prPrec i 0 (concatD [doc (showString "cat") , prt 0 id , doc (showString "[") , prt 0 decls , doc (showString "]") , doc (showString "=") , prt 0 cidents])
-   AbsDFun id exp0 exp -> prPrec i 0 (concatD [doc (showString "fun") , prt 0 id , doc (showString ":") , prt 0 exp0 , doc (showString "=") , prt 0 exp])
-   AbsDTrans id exp -> prPrec i 0 (concatD [doc (showString "transfer") , prt 0 id , doc (showString "=") , prt 0 exp])
-   ResDPar id pardefs -> prPrec i 0 (concatD [doc (showString "param") , prt 0 id , doc (showString "=") , prt 0 pardefs])
-   ResDOper id ctype term -> prPrec i 0 (concatD [doc (showString "oper") , prt 0 id , doc (showString ":") , prt 0 ctype , doc (showString "=") , prt 0 term])
-   CncDCat id ctype term0 term -> prPrec i 0 (concatD [doc (showString "lincat") , prt 0 id , doc (showString "=") , prt 0 ctype , doc (showString "=") , prt 0 term0 , doc (showString ";") , prt 0 term])
-   CncDFun id cident argvars term0 term -> prPrec i 0 (concatD [doc (showString "lin") , prt 0 id , doc (showString ":") , prt 0 cident , doc (showString "=") , doc (showString "\\") , prt 0 argvars , doc (showString "->") , prt 0 term0 , doc (showString ";") , prt 0 term])
-   AnyDInd id0 status id -> prPrec i 0 (concatD [prt 0 id0 , prt 0 status , doc (showString "in") , prt 0 id])
+   AbsDCat id decls cidents -> prPrec i 0 (concatD [docs (showString "cat") , prt 0 id , doc (showString "[") , prt 0 decls , doc (showString "]") , doc (showString "=") , prt 0 cidents])
+   AbsDFun id exp0 exp -> prPrec i 0 (concatD [docs (showString "fun") , prt 0 id , doc (showString ":") , prt 0 exp0 , doc (showString "=") , prt 0 exp])
+   AbsDTrans id exp -> prPrec i 0 (concatD [docs (showString "transfer") , prt 0 id , doc (showString "=") , prt 0 exp])
+   ResDPar id pardefs -> prPrec i 0 (concatD [docs (showString "param") , prt 0 id , doc (showString "=") , prt 0 pardefs])
+   ResDOper id ctype term -> prPrec i 0 (concatD [docs (showString "oper") , prt 0 id , doc (showString ":") , prt 0 ctype , doc (showString "=") , prt 0 term])
+   CncDCat id ctype term0 term -> prPrec i 0 (concatD [docs (showString "lincat") , prt 0 id , doc (showString "=") , prt 0 ctype , doc (showString "=") , prt 0 term0 , doc (showString ";") , prt 0 term])
+   CncDFun id cident argvars term0 term -> prPrec i 0 (concatD [docs (showString "lin") , prt 0 id , doc (showString ":") , prt 0 cident , doc (showString "=") , doc (showString "\\") , prt 0 argvars , doc (showString "->") , prt 0 term0 , doc (showString ";") , prt 0 term])
+   AnyDInd id0 status id -> prPrec i 0 (concatD [prt 0 id0 , prt 0 status , docs (showString "in") , prt 0 id])
 
   prtList es = case es of
    [] -> (concatD [])
-   x:xs -> (concatD [prt 0 x , doc (showString ";"), doc (showString "*NEW") , prt 0 xs]) -- H
+   x:xs -> (concatD [prt 0 x , doc (showString ";"), doc (showString "*") , prt 0 xs]) -- H
 
 
 instance Print ParDef where
@@ -170,7 +190,7 @@ instance Print ParDef where
 
 instance Print Status where
   prt i e = case e of
-   Canon  -> prPrec i 0 (concatD [doc (showString "data")])
+   Canon  -> prPrec i 0 (concatD [docs (showString "data")])
    NonCan  -> prPrec i 0 (concatD [])
 
 
@@ -188,13 +208,13 @@ instance Print Exp where
    EProd id exp0 exp -> prPrec i 0 (concatD [doc (showString "(") , prt 0 id , doc (showString ":") , prt 0 exp0 , doc (showString ")") , doc (showString "->") , prt 0 exp])
    EAbs id exp -> prPrec i 0 (concatD [doc (showString "\\") , prt 0 id , doc (showString "->") , prt 0 exp])
    EAtom atom -> prPrec i 2 (concatD [prt 0 atom])
-   EData  -> prPrec i 2 (concatD [doc (showString "data")])
+   EData  -> prPrec i 2 (concatD [docs (showString "data")])
    EEq equations -> prPrec i 0 (concatD [doc (showString "{") , prt 0 equations , doc (showString "}")])
 
 
 instance Print Sort where
   prt i e = case e of
-   SType  -> prPrec i 0 (concatD [doc (showString "Type")])
+   SType  -> prPrec i 0 (concatD [docs (showString "Type")])
 
 
 instance Print Equation where
@@ -242,8 +262,8 @@ instance Print CType where
    RecType labellings -> prPrec i 0 (concatD [doc (showString "{") , prt 0 labellings , doc (showString "}")])
    Table ctype0 ctype -> prPrec i 0 (concatD [doc (showString "(") , prt 0 ctype0 , doc (showString "=>") , prt 0 ctype , doc (showString ")")])
    Cn cident -> prPrec i 0 (concatD [prt 0 cident])
-   TStr  -> prPrec i 0 (concatD [doc (showString "Str")])
-   TInts n -> prPrec i 0 (concatD [doc (showString "Ints") , prt 0 n])
+   TStr  -> prPrec i 0 (concatD [docs (showString "Str")])
+   TInts n -> prPrec i 0 (concatD [docs (showString "Ints") , prt 0 n])
 
   prtList es = case es of
    [] -> (concatD [])
@@ -266,11 +286,11 @@ instance Print Term where
    LI id -> prPrec i 2 (concatD [doc (showString "$") , prt 0 id])
    R assigns -> prPrec i 2 (concatD [doc (showString "{") , prt 0 assigns , doc (showString "}")])
    P term label -> prPrec i 1 (concatD [prt 2 term , doc (showString ".") , prt 0 label])
-   T ctype cases -> prPrec i 1 (concatD [doc (showString "table") , prt 0 ctype , doc (showString "{") , prt 0 cases , doc (showString "}")])
-   V ctype terms -> prPrec i 1 (concatD [doc (showString "table") , prt 0 ctype , doc (showString "[") , prt 2 terms , doc (showString "]")])
+   T ctype cases -> prPrec i 1 (concatD [docs (showString "table") , prt 0 ctype , doc (showString "{") , prt 0 cases , doc (showString "}")])
+   V ctype terms -> prPrec i 1 (concatD [docs (showString "table") , prt 0 ctype , doc (showString "[") , prt 2 terms , doc (showString "]")])
    S term0 term -> prPrec i 1 (concatD [prt 1 term0 , doc (showString "!") , prt 2 term])
    C term0 term -> prPrec i 0 (concatD [prt 0 term0 , doc (showString "++") , prt 1 term])
-   FV terms -> prPrec i 1 (concatD [doc (showString "variants") , doc (showString "{") , prt 2 terms , doc (showString "}")])
+   FV terms -> prPrec i 1 (concatD [docs (showString "variants") , doc (showString "{") , prt 2 terms , doc (showString "}")])
    EInt n -> prPrec i 2 (concatD [prt 0 n])
    K tokn -> prPrec i 2 (concatD [prt 0 tokn])
    E  -> prPrec i 2 (concatD [doc (showString "[") , doc (showString "]")])
@@ -282,7 +302,7 @@ instance Print Term where
 instance Print Tokn where
   prt i e = case e of
    KS str -> prPrec i 0 (concatD [prt 0 str])
-   KP strs variants -> prPrec i 0 (concatD [doc (showString "[") , doc (showString "pre") , prt 0 strs , doc (showString "{") , prt 0 variants , doc (showString "}") , doc (showString "]")])
+   KP strs variants -> prPrec i 0 (concatD [doc (showString "[") , docs (showString "pre") , prt 0 strs , doc (showString "{") , prt 0 variants , doc (showString "}") , doc (showString "]")])
    KM str -> prPrec i 0 (concatD [prt 0 str])
 
 
@@ -333,7 +353,7 @@ instance Print Patt where
   prt i e = case e of
    PC cident patts -> prPrec i 0 (concatD [doc (showString "(") , prt 0 cident , prt 0 patts , doc (showString ")")])
    PV id -> prPrec i 0 (concatD [prt 0 id])
-   PW  -> prPrec i 0 (concatD [doc (showString "_")])
+   PW  -> prPrec i 0 (concatD [docs (showString "_")])
    PR pattassigns -> prPrec i 0 (concatD [doc (showString "{") , prt 0 pattassigns , doc (showString "}")])
    PI n -> prPrec i 0 (concatD [prt 0 n])
 
diff --git a/src/GF/Canon/Subexpressions.hs b/src/GF/Canon/Subexpressions.hs
new file mode 100644
index 000000000..0bc8d546d
--- /dev/null
+++ b/src/GF/Canon/Subexpressions.hs
@@ -0,0 +1,152 @@
+----------------------------------------------------------------------
+-- |
+-- Module      : Subexpressions
+-- Maintainer  : AR
+-- Stability   : (stable)
+-- Portability : (portable)
+--
+-- > CVS $Date: 2005/09/18 22:55:46 $ 
+-- > CVS $Author: aarne $
+-- > CVS $Revision: 1.1 $
+--
+-- Common subexpression elimination.
+-- all tables. AR 18\/9\/2005.
+-----------------------------------------------------------------------------
+
+module GF.Canon.Subexpressions where -- (subelimCanon) where
+
+import GF.Canon.AbsGFC
+import GF.Infra.Ident
+import GF.Canon.GFC
+import GF.Canon.Look
+import GF.Grammar.PrGrammar
+import GF.Canon.CMacros as C
+import GF.Data.Operations
+import qualified GF.Infra.Modules as M
+
+import Control.Monad
+import Data.FiniteMap
+import Data.List
+
+type TermList = FiniteMap Term (Int,Int) -- number of occs, id
+
+type TermM a = STM (TermList,Int) a
+
+prSubtermStat :: CanonGrammar -> String
+prSubtermStat gr = unlines [prt mo ++++ expsIn mo js | (mo,js) <- mos] where
+  mos = [(i, tree2list (M.jments m)) | (i, M.ModMod m) <- M.modules gr, M.isModCnc m]
+  expsIn mo js = err id id $ do
+   (js', (tree,nu)) <- appSTM (getSubtermsMod mo js) (emptyFM,0)
+   let list0 = filter ((>1) . fst . snd) $ fmToList tree
+   let list1 = sortBy (\ (_,(m,_)) (_,(n,_)) -> compare n m) list0
+   return $ unlines [show n ++ "\t" ++ prt trm | (trm,(n,_)) <- list1]
+
+elimSubtermsMod :: (Ident,CanonModInfo) -> Err (Ident, CanonModInfo)
+elimSubtermsMod (mo,m) = case m of
+  M.ModMod (M.Module mt st fs me ops js) -> do
+    (js',(tree,_)) <- appSTM (getSubtermsMod mo (tree2list js)) (emptyFM,0)
+    js2 <- liftM buildTree $ addSubexpConsts tree js'
+    return (mo,M.ModMod (M.Module mt st fs me ops js2))
+  _ -> return (mo,m)
+
+addSubexpConsts :: FiniteMap Term (Int,Int) -> [(Ident,Info)] -> Err [(Ident,Info)]
+addSubexpConsts tree lins = do
+  let opers = [oper id trm | (trm,(nu,id)) <- list, nu > 1]
+  mapM filterOne $ opers ++ lins
+ where
+
+   filterOne (f,def) = case def of
+     CncFun ci xs trm pn -> do
+       trm' <- recomp trm
+       return (f,CncFun ci xs trm' pn)
+     ResOper ty trm -> do
+       trm' <- recomp trm
+       return (f,ResOper ty trm')
+     _ -> return (f,def)
+   recomp t = case t of
+     I (CIQ _ e) -> do
+       (nu,exp) <- getCount e
+       if nu > 1 then return t else recomp exp 
+     _ -> composOp recomp t
+   list = fmToList tree
+   tree' = listToFM $ map (\ (e, (nu,id)) -> (ident id,(nu,e))) $ list
+   getCount e = case lookupFM tree' e of
+     Just v -> return v
+     _ -> return (2,undefined)  --- global from elsewhere: keep
+   oper id trm = (ident id, ResOper TStr trm) --- type TStr does not matter
+
+getSubtermsMod :: Ident -> [(Ident,Info)] -> TermM [(Ident,Info)]
+getSubtermsMod mo js = do
+  js' <- mapM getInfo js
+  tryAgain
+  tryAgain --- do twice instead of fixpoint iteration
+  return js' ----
+ where
+   getInfo fi@(f,i) = case i of
+     CncFun ci xs trm pn -> do
+       trm' <- getSubterms mo trm
+       return $ (f,CncFun ci xs trm' pn)
+     _ -> return fi
+   tryAgain = do
+     (ts,i) <- readSTM
+     let trms = map fst $ fmToList ts
+     mapM (getSubtermsAgain mo) trms
+     (ts',i') <- readSTM
+     if False ---- i' > i || count ts' > count ts 
+       then tryAgain
+       else return ()
+   count = sum . map (fst . snd) . fmToList -- how many subterms there are
+
+getSubterms :: Ident -> Term -> TermM Term
+getSubterms mo t = case t of
+  Par _ (_:_) -> add t
+  T _ cs      -> add t
+  V _ ts      -> add t
+  K (KP _ _)  -> add t
+  _ -> composOp (getSubterms mo) t
+ where
+   add t = do
+     (ts,i) <- readSTM
+     let 
+       ((count,id),next) = case lookupFM ts t of
+         Just (nu,id) -> ((nu+1,id), i)
+         _ ->            ((1,   i ), i+1)
+     writeSTM (addToFM ts t (count,id), next)
+     return $ I $ cident mo id
+
+-- this is used in later phases of iteration
+getSubtermsAgain :: Ident -> Term -> TermM Term
+getSubtermsAgain mo t = case t of
+  T ty cs -> do
+    let (ps,ts) = unzip [(p,t) | Cas p t <- cs]
+    ts' <- mapM (getSubterms mo) ts
+    return $ T ty $ [Cas p t | (p,t) <- zip ps ts']
+  V ty ts -> do
+    liftM (V ty) $ mapM (getSubterms mo) ts
+  Par _ _ -> return t
+  K _     -> return t
+  _ -> getSubterms mo t
+
+ident :: Int -> Ident
+ident i = identC ("A''" ++ show i) ---
+
+cident :: Ident -> Int -> CIdent
+cident mo = CIQ mo . ident
+
+
+unSubelimCanon :: CanonGrammar -> CanonGrammar
+unSubelimCanon gr@(M.MGrammar modules) = 
+    M.MGrammar $ map unparModule modules where 
+
+  unparModule (i,m) = case m of
+    M.ModMod (M.Module mt@(M.MTConcrete _) st fs me ops js) ->
+      (i, M.ModMod (M.Module mt st fs me ops (mapTree unparInfo js)))
+    _ -> (i,m)
+
+  unparInfo (c,info) = case info of
+    CncFun k xs t m -> (c, CncFun k xs (unparTerm t) m)
+    _ -> (c,info)
+
+  unparTerm t = case t of
+    I c -> errVal t $ liftM unparTerm $ lookupGlobal gr c 
+    _ -> C.composSafeOp unparTerm t
diff --git a/src/GF/Compile/Compile.hs b/src/GF/Compile/Compile.hs
index d5874d0e2..13710791d 100644
--- a/src/GF/Compile/Compile.hs
+++ b/src/GF/Compile/Compile.hs
@@ -5,9 +5,9 @@
 -- Stability   : (stable)
 -- Portability : (portable)
 --
--- > CVS $Date: 2005/06/10 21:04:01 $
+-- > CVS $Date: 2005/09/18 22:55:46 $
 -- > CVS $Author: aarne $
--- > CVS $Revision: 1.41 $
+-- > CVS $Revision: 1.42 $
 --
 -- The top-level compilation chain from source file to gfc\/gfr.
 -----------------------------------------------------------------------------
@@ -38,6 +38,7 @@ import GF.Compile.CheckGrammar
 import GF.Compile.Optimize
 import GF.Compile.GrammarToCanon
 import GF.Canon.Share
+import GF.Canon.Subexpressions (elimSubtermsMod)
 
 import qualified GF.Canon.CanonToGrammar as CG
 
@@ -283,7 +284,7 @@ generateModuleCode opts path minfo@(name,info) = do
   minfo0     <- ioeErr $ redModInfo minfo
   let oopts = addOptions opts (iOpts (flagsModule minfo))
       optim = maybe "share" id $ getOptVal oopts useOptimizer
-  minfo'     <- return $ 
+  minfo1     <- return $ 
     case optim of
       "parametrize" -> shareModule paramOpt minfo0  -- parametrization and sharing
       "values"      -> shareModule valOpt minfo0    -- tables as courses-of-values
@@ -292,6 +293,12 @@ generateModuleCode opts path minfo@(name,info) = do
       "none"        -> minfo0                       -- no optimization
       _             -> shareModule shareOpt minfo0  -- sharing; default
 
+  -- do common subexpression elimination if required by flag "subs"
+  minfo' <- 
+    if oElem elimSubs opts
+      then ioeErr $ elimSubtermsMod minfo1
+      else return minfo1
+
   -- for resource, also emit gfr. 
   --- Also for incomplete, to create timestamped gfc/gfr files
   case info of
diff --git a/src/GF/Compile/ShellState.hs b/src/GF/Compile/ShellState.hs
index a484b50e8..0d4c59652 100644
--- a/src/GF/Compile/ShellState.hs
+++ b/src/GF/Compile/ShellState.hs
@@ -5,9 +5,9 @@
 -- Stability   : (stable)
 -- Portability : (portable)
 --
--- > CVS $Date: 2005/09/01 09:53:18 $ 
--- > CVS $Author: peb $
--- > CVS $Revision: 1.46 $
+-- > CVS $Date: 2005/09/18 22:55:46 $ 
+-- > CVS $Author: aarne $
+-- > CVS $Revision: 1.47 $
 --
 -- (Description of the module)
 -----------------------------------------------------------------------------
@@ -21,6 +21,7 @@ import GF.Grammar.Macros
 import GF.Grammar.MMacros
 
 import GF.Canon.Look
+import GF.Canon.Subexpressions
 import GF.Grammar.LookAbs
 import GF.Compile.ModDeps
 import qualified GF.Infra.Modules as M
@@ -185,7 +186,8 @@ updateShellState opts mcnc sh ((_,sgr,gr),rts) = do
   let concrs = maybe [] (M.allConcretes cgr) abstr0
       concr0 = ifNull Nothing (return . head) concrs
       notInrts f = notElem f $ map fst rts
-  cfs <- mapM (canon2cf opts cgr) concrs --- would not need to update all...
+      sub = if oElem elimSubs opts then unSubelimCanon else id
+  cfs <- mapM (canon2cf opts (sub cgr)) concrs --- why need to update all...
 
   let pinfosOld = map (CnvOld.pInfo opts cgr) concrs  -- peb 18/6 (OBSOLETE)
 
diff --git a/src/GF/Infra/Option.hs b/src/GF/Infra/Option.hs
index 4e6e66b02..f00ecd63a 100644
--- a/src/GF/Infra/Option.hs
+++ b/src/GF/Infra/Option.hs
@@ -5,9 +5,9 @@
 -- Stability   : (stable)
 -- Portability : (portable)
 --
--- > CVS $Date: 2005/06/10 21:04:01 $ 
+-- > CVS $Date: 2005/09/18 22:55:46 $ 
 -- > CVS $Author: aarne $
--- > CVS $Revision: 1.30 $
+-- > CVS $Revision: 1.31 $
 --
 -- Options and flags used in GF shell commands and files.
 --
@@ -189,6 +189,7 @@ checkCirc   = iOpt "nocirc"
 noCheckCirc = iOpt "nocheckcirc"
 lexerByNeed = iOpt "cflexer"
 useUTF8id   = iOpt "utf8id"
+elimSubs    = iOpt "subs"
 
 -- ** linearization
 
diff --git a/src/GF/UseGrammar/Custom.hs b/src/GF/UseGrammar/Custom.hs
index 19af14984..c7c68362b 100644
--- a/src/GF/UseGrammar/Custom.hs
+++ b/src/GF/UseGrammar/Custom.hs
@@ -5,9 +5,9 @@
 -- Stability   : (stable)
 -- Portability : (portable)
 --
--- > CVS $Date: 2005/09/14 16:26:22 $ 
+-- > CVS $Date: 2005/09/18 22:55:46 $ 
 -- > CVS $Author: aarne $
--- > CVS $Revision: 1.73 $
+-- > CVS $Revision: 1.74 $
 --
 -- A database for customizable GF shell commands. 
 --
@@ -82,6 +82,7 @@ import qualified GF.Conversion.Types as CnvTypes
 import qualified GF.Conversion.Haskell as CnvHaskell
 import qualified GF.Conversion.Prolog as CnvProlog
 import GF.Canon.Unparametrize
+import GF.Canon.Subexpressions
 
 import GF.Canon.GFC
 import qualified GF.Canon.MkGFC as MC
@@ -260,6 +261,7 @@ customGrammarPrinter =
   ,(strCI "printnames", C.prPrintnamesGrammar . stateGrammarST)
   ,(strCI "stat",    prStatistics . stateGrammarST)
   ,(strCI "unpar",   prCanon . unparametrizeCanon . stateGrammarST)
+  ,(strCI "subs",    prSubtermStat . stateGrammarST)
 
 {- ----
    (strCI "gf",      prt  . st2grammar . stateGrammarST)  -- DEFAULT