diff --git a/lilypond.cabal b/lilypond.cabal
--- a/lilypond.cabal
+++ b/lilypond.cabal
@@ -1,6 +1,6 @@
 
 name:                   lilypond
-version:                1.6.2
+version:                1.7
 author:                 Hans Hoglund
 maintainer:             Hans Hoglund <hans@hanshoglund.se>
 license:                BSD3
@@ -28,8 +28,8 @@
                         process,
                         data-default,
                         prettify,
-                        music-pitch-literal     == 1.6.2,
-                        music-dynamics-literal  == 1.6.2
+                        music-pitch-literal     == 1.7,
+                        music-dynamics-literal  == 1.7
     exposed-modules:    Music.Lilypond
                         Music.Lilypond.Pitch
                         Music.Lilypond.Dynamics
diff --git a/src/Music/Lilypond.hs b/src/Music/Lilypond.hs
--- a/src/Music/Lilypond.hs
+++ b/src/Music/Lilypond.hs
@@ -31,6 +31,7 @@
         -- ** Attributes
         Value,
         toValue,
+        toLiteralValue,
 
         -- ** Articulation and dynamics
         PostEvent(..),
@@ -200,8 +201,52 @@
     | New String (Maybe String) Music               -- ^ New expression.
     | Context String (Maybe String) Music           -- ^ Context expression.
     | Set String Value                            
+    | Override String Value
+    | Revert String
     deriving (Eq, Show)
 
+foldMusic :: (Music -> Music) -> Music -> Music
+foldMusic f = go
+    where
+        go (Sequential ms)      = Sequential (fmap go ms)                          
+        go (Simultaneous b ms)  = Simultaneous b (fmap go ms)                     
+        go (Repeat b i m qmm)   = Repeat b i m (fmap (go *** go) qmm)  
+        go (Tremolo n m)        = Tremolo n (go m)                             
+        go (Times r m)          = Times r (go m)                          
+        go (Transpose p p2 m)   = Transpose p p2 (go m)                   
+        go (Relative p m)       = Relative p (go m)                          
+        go (New s v m)          = New s v (go m)               
+        go (Context s v m)      = Context s v (go m)
+        go x = f x
+
+foldMusic' :: (Music -> Music) -- Rest Note Chord
+           -> (Music -> Music) -- Other non-recursive
+           -> (Music -> Music) -- Recursive
+           -> Music -> Music
+foldMusic' f g h = go
+    where               
+        go m@(Rest _ _)           = f m
+        go m@(Note _ _ _)         = f m
+        go m@(Chord _ _ _)        = f m
+        go m@(Clef _)             = g m
+        go m@(Key _ _)            = g m
+        go m@(Time _ _)           = g m
+        go m@(Breathe _)          = g m
+        go m@(Tempo _ _)          = g m
+        go m@(Set _ _)            = g m
+        go m@(Override _ _)       = g m
+        go m@(Revert _)           = g m
+        go (Sequential ms)      = Sequential (fmap h ms)                          
+        go (Simultaneous b ms)  = Simultaneous b (fmap h ms)                     
+        go (Repeat b i m qmm)   = Repeat b i m (fmap (h *** h) qmm)  
+        go (Tremolo n m)        = Tremolo n (h m)                             
+        go (Times r m)          = Times r (h m)                          
+        go (Transpose p p2 m)   = Transpose p p2 (h m)                   
+        go (Relative p m)       = Relative p (h m)                          
+        go (New s v m)          = New s v (h m)               
+        go (Context s v m)      = Context s v (h m)
+
+
 instance Pretty Music where
     pretty (Rest d p)       = "r" <> pretty d <> prettyList p
 
@@ -260,8 +305,14 @@
         "\\context" <+> string typ <+> pretty name <+> pretty x
 
     pretty (Set name val) =
-        "\\set" <+> string name <+> "=" <+> (string . show) val
+        "\\set" <+> string name <+> "=" <+> pretty val
 
+    pretty (Override name val) =
+        "\\override" <+> string name <+> "=" <+> pretty val
+
+    pretty (Revert name) =
+        "\\revert" <+> string name
+
     -- pretty _                        = notImpl "Unknown music expression"
 
     prettyList                      = hsep . fmap pretty
@@ -605,10 +656,11 @@
 
 
 addPost :: PostEvent -> Music -> Music
-addPost a (Rest d es)     = Rest d (es ++ [a])
-addPost a (Note n d es)   = Note n d (es ++ [a])
-addPost a (Chord ns d es) = Chord ns d (es ++ [a])
-addPost a m               = m
+addPost a = foldMusic' (addPost' a) id (addPost a)
+  where
+    addPost' a (Rest d es)     = Rest d (es ++ [a])
+    addPost' a (Note n d es)   = Note n d (es ++ [a])
+    addPost' a (Chord ns d es) = Chord ns d (es ++ [a])
 
 addText :: String -> Music -> Music
 addText s = addPost (Text def s)
@@ -789,20 +841,6 @@
 addVarCoda = addArticulation VarCoda
 
 
-
-foldMusic :: (Music -> Music) -> Music -> Music
-foldMusic f = go
-    where
-        go (Sequential ms)      = Sequential (fmap go ms)                          
-        go (Simultaneous b ms)  = Simultaneous b (fmap go ms)                     
-        go (Repeat b i m qmm)   = Repeat b i m (fmap (go *** go) qmm)  
-        go (Tremolo n m)        = Tremolo n (go m)                             
-        go (Times r m)          = Times r (go m)                          
-        go (Transpose p p2 m)   = Transpose p p2 (go m)                   
-        go (Relative p m)       = Relative p (go m)                          
-        go (New s v m)          = New s v (go m)               
-        go (Context s v m)      = Context s v (go m)
-        go x = f x
 
 removeSingleChords :: Music -> Music
 removeSingleChords = foldMusic go
diff --git a/src/Music/Lilypond/Dynamics.hs b/src/Music/Lilypond/Dynamics.hs
--- a/src/Music/Lilypond/Dynamics.hs
+++ b/src/Music/Lilypond/Dynamics.hs
@@ -57,6 +57,7 @@
         2.5    -> FF
         3.5    -> FFF
         4.5    -> FFFF
-    fromDynamics _ = error "fromDynamics: Unsupported literal for MusicXml.Dynamics"
+        x      -> error $ "Lilypond.Dynamics: Strange value " ++ show x
+    fromDynamics _ = error "Lilypond.Dynamics: Unsupported literal"
 
 
diff --git a/src/Music/Lilypond/Value.hs b/src/Music/Lilypond/Value.hs
--- a/src/Music/Lilypond/Value.hs
+++ b/src/Music/Lilypond/Value.hs
@@ -19,6 +19,7 @@
 module Music.Lilypond.Value (
         Value,
         toValue,
+        toLiteralValue,
   ) where
 
 import Data.String
@@ -39,7 +40,7 @@
 -- > \set Staff.instrumentName = "Violin I"
 -- > \set Staff.instrumentName = 2
 --
-data Value = forall a . Show a => Value a
+data Value = forall a . Show a => Value a | Literal String
 
 instance IsString Value where
     fromString = toValue
@@ -64,9 +65,16 @@
 instance Eq Value where
     a == b  = show a == show b
 
+instance Pretty Value where
+  pretty (Value x)   = (string . show) x
+  pretty (Literal x) = string x
+
 toValue :: Show a => a -> Value
 toValue = Value
 
+-- | As 'toValue', but not quoting strings. Handy for scheme literals such as @#red@.
+toLiteralValue :: String -> Value
+toLiteralValue = Literal
 
 
 noOverloading :: String -> a