diff --git a/ChangeLog.md b/ChangeLog.md
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--- /dev/null
+++ b/ChangeLog.md
@@ -0,0 +1,3 @@
+# Changelog for postgresql-common
+
+## Unreleased changes
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,30 @@
+Copyright Ian Duncan (c) 2018
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Ian Duncan nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.md b/README.md
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--- /dev/null
+++ b/README.md
@@ -0,0 +1,1 @@
+# postgresql-common
diff --git a/Setup.hs b/Setup.hs
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--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/postgresql-common.cabal b/postgresql-common.cabal
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--- /dev/null
+++ b/postgresql-common.cabal
@@ -0,0 +1,56 @@
+-- This file has been generated from package.yaml by hpack version 0.28.2.
+--
+-- see: https://github.com/sol/hpack
+--
+-- hash: 4c369b6db498a176311e660d7eb0528d548c5f9e7f244fd667b4b4af76d6e669
+
+name:           postgresql-common
+version:        0.1.0.0
+synopsis:       Library for sharing common PostgreSQL types across Haskell PostgreSQL libraries.
+description:    Please see the README on GitHub at <https://github.com/iand675/postgresql-common#readme>
+homepage:       https://github.com/iand675/postgresql-common#readme
+bug-reports:    https://github.com/iand675/postgresql-common/issues
+author:         Ian Duncan
+maintainer:     ian@iankduncan.com
+copyright:      Ian Duncan
+license:        BSD3
+license-file:   LICENSE
+build-type:     Simple
+cabal-version:  >= 1.10
+extra-source-files:
+    ChangeLog.md
+    README.md
+
+source-repository head
+  type: git
+  location: https://github.com/iand675/postgresql-common
+
+library
+  exposed-modules:
+      Database.PostgreSQL.Types.LSN
+  other-modules:
+      Paths_postgresql_common
+  hs-source-dirs:
+      src
+  build-depends:
+      attoparsec
+    , base >=4.7 && <5
+    , bytestring
+    , postgresql-simple
+  default-language: Haskell2010
+
+test-suite postgresql-common-test
+  type: exitcode-stdio-1.0
+  main-is: Spec.hs
+  other-modules:
+      Paths_postgresql_common
+  hs-source-dirs:
+      test
+  ghc-options: -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      attoparsec
+    , base >=4.7 && <5
+    , bytestring
+    , postgresql-common
+    , postgresql-simple
+  default-language: Haskell2010
diff --git a/src/Database/PostgreSQL/Types/LSN.hs b/src/Database/PostgreSQL/Types/LSN.hs
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--- /dev/null
+++ b/src/Database/PostgreSQL/Types/LSN.hs
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+module Database.PostgreSQL.Types.LSN
+    ( LSN(..)
+    -- * Utilities
+    , encodeLSN
+    , decodeLSN
+    , lsnParser
+    ) where
+
+import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString.Lazy as BL
+import qualified Data.ByteString.Lazy.Builder as Builder
+import Data.ByteString.Lazy.Builder.ASCII (word32Hex, word32HexFixed)
+import Data.Monoid ((<>))
+import Data.Word
+import Data.Attoparsec.ByteString.Char8
+
+-- TODO Ord instance
+data LSN = LSN !Word32 {- ^ Filepart -} !Word32 {- ^ Offset -}
+  deriving (Show, Eq)
+
+instance Ord LSN where
+  compare (LSN l0 r0) (LSN l1 r1)
+    | l0 > l1 || (l0 == l1 && r0 > r1) = GT
+    | l0 < l1 || (l0 == l1 && r0 < r1) = LT
+    | otherwise = EQ
+
+lsnParser :: Parser LSN
+lsnParser = LSN <$> (hexadecimal <* char '/') <*> hexadecimal
+
+decodeLSN :: ByteString -> Either String LSN
+decodeLSN = parseOnly lsnParser
+
+encodeLSN :: LSN -> ByteString
+encodeLSN (LSN filepart off) = BL.toStrict $ Builder.toLazyByteString (word32Hex filepart <> Builder.char7 '/' <> word32Hex off)
+
+-- instance ToField LSN where
+
+-- instance FromField LSN where
diff --git a/test/Spec.hs b/test/Spec.hs
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--- /dev/null
+++ b/test/Spec.hs
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+main :: IO ()
+main = putStrLn "Test suite not yet implemented"