diff --git a/Biobase/Primary/Letter.hs b/Biobase/Primary/Letter.hs
--- a/Biobase/Primary/Letter.hs
+++ b/Biobase/Primary/Letter.hs
@@ -12,8 +12,7 @@
 import           Data.Ix (Ix(..))
 import           Data.Serialize (Serialize(..))
 import           Data.String (IsString(..))
-import           Data.Vector.Fusion.Stream.Monadic (map,flatten,Step(..))
-import           Data.Vector.Fusion.Stream.Size (Size (Unknown))
+import           Data.Vector.Fusion.Stream.Monadic (map,Step(..))
 import           Data.Vector.Unboxed.Deriving
 import           GHC.Base (remInt,quotInt)
 import           GHC.Generics (Generic)
@@ -88,7 +87,7 @@
   {-# Inline inBounds #-}
 
 instance IndexStream z => IndexStream (z:.Letter l) where
-  streamUp (ls:.Letter l) (hs:.Letter h) = flatten mk step Unknown $ streamUp ls hs
+  streamUp (ls:.Letter l) (hs:.Letter h) = flatten mk step $ streamUp ls hs
     where mk z = return (z,l)
           step (z,k)
             | k > h     = return $ Done
@@ -96,7 +95,7 @@
           {-# Inline [0] mk   #-}
           {-# Inline [0] step #-}
   {-# Inline streamUp #-}
-  streamDown (ls:.Letter l) (hs:.Letter h) = flatten mk step Unknown $ streamDown ls hs
+  streamDown (ls:.Letter l) (hs:.Letter h) = flatten mk step $ streamDown ls hs
     where mk z = return (z,h)
           step (z,k)
             | k < l     = return $ Done
diff --git a/Biobase/Secondary/Vienna.hs b/Biobase/Secondary/Vienna.hs
--- a/Biobase/Secondary/Vienna.hs
+++ b/Biobase/Secondary/Vienna.hs
@@ -9,8 +9,7 @@
 import           Data.Primitive.Types
 import           Data.Serialize (Serialize(..))
 import           Data.Tuple (swap)
-import           Data.Vector.Fusion.Stream.Monadic (map,flatten,Step(..))
-import           Data.Vector.Fusion.Stream.Size (Size (Unknown))
+import           Data.Vector.Fusion.Stream.Monadic (map,Step(..))
 import           Data.Vector.Unboxed.Deriving
 import           GHC.Base (remInt,quotInt)
 import           GHC.Generics (Generic)
@@ -51,7 +50,7 @@
   {-# Inline inBounds #-}
 
 instance IndexStream z => IndexStream (z:.ViennaPair) where
-  streamUp (ls:.ViennaPair l) (hs:.ViennaPair h) = flatten mk step Unknown $ streamUp ls hs
+  streamUp (ls:.ViennaPair l) (hs:.ViennaPair h) = flatten mk step $ streamUp ls hs
     where mk z = return (z,l)
           step (z,k)
             | k > h     = return $ Done
@@ -59,7 +58,7 @@
           {-# Inline [0] mk   #-}
           {-# Inline [0] step #-}
   {-# Inline streamUp #-}
-  streamDown (ls:.ViennaPair l) (hs:.ViennaPair h) = flatten mk step Unknown $ streamDown ls hs
+  streamDown (ls:.ViennaPair l) (hs:.ViennaPair h) = flatten mk step $ streamDown ls hs
     where mk z = return (z,h)
           step (z,k)
             | k < l     = return $ Done
diff --git a/BiobaseXNA.cabal b/BiobaseXNA.cabal
--- a/BiobaseXNA.cabal
+++ b/BiobaseXNA.cabal
@@ -1,5 +1,5 @@
 name:           BiobaseXNA
-version:        0.9.2.0
+version:        0.9.2.1
 author:         Christian Hoener zu Siederdissen
 maintainer:     choener@bioinf.uni-leipzig.de
 homepage:       https://github.com/choener/BiobaseXNA
@@ -41,11 +41,14 @@
   changelog.md
   README.md
 
+data-files:
+  sources/iupac-nucleotides
 
 
+
 library
   build-depends: base                     >= 4.7      && < 4.9
-               , aeson                    >= 0.8      && < 0.10
+               , aeson                    >= 0.8      && < 0.11
                , bimaps                   >= 0.0.0.2  && < 0.0.1.0
                , binary                   >= 0.7      && < 0.8
                , bytes                    >= 0.15     && < 0.16
@@ -55,15 +58,15 @@
                , containers               >= 0.5      && < 0.6
                , csv                      >= 0.1      && < 0.2
                , deepseq                  >= 1.3      && < 1.5
-               , file-embed               >= 0.0.8    && < 0.0.9
+               , file-embed               >= 0.0.8    && < 0.0.10
                , hashable                 >= 1.2      && < 1.3
-               , lens                     >= 4.0      && < 4.13
+               , lens                     >= 4.0      && < 4.14
                , primitive                >= 0.5      && < 0.7
-               , PrimitiveArray           >= 0.6.0    && < 0.6.2
+               , PrimitiveArray           >= 0.7.0    && < 0.7.1
                , split                    >= 0.2      && < 0.3
                , text                     >= 1.0      && < 1.3
                , tuple                    >= 0.3      && < 0.4
-               , vector                   >= 0.10     && < 0.11
+               , vector                   >= 0.10     && < 0.12
                , vector-binary-instances  >= 0.2      && < 0.3
                , vector-th-unbox          >= 0.2      && < 0.3
   exposed-modules:
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -2,7 +2,18 @@
 
 # BiobaseXNA
 
-Efficient encoding of biological sequences.
+Efficient encoding of (short) biological sequences. This package ist designed
+to deal with *in-memory* snippets of DNA, RNA, and amino acids. The encoding is
+geared toward time-efficiency, not necessarily space efficiency (we use Int's
+for encoding characters, not the smallest type possible).
+
+Additional modules provide conversion capabilities between different types of
+characters according to biological laws, and some biochemical constraint
+information. The latter includes canonical and non-canonical pairing
+information for RNA.
+
+Actual energy parameters for pairings are provided by other packages, for
+example BiobaseTurner for the loop energy model with measured parameters.
 
 
 
diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,3 +1,7 @@
+0.9.2.1
+
+- stack.yaml, some version bumping
+
 0.9.2.0
 -------