diff --git a/biophd.cabal b/biophd.cabal
--- a/biophd.cabal
+++ b/biophd.cabal
@@ -1,5 +1,5 @@
 Name:                biophd
-Version:             0.0.1
+Version:             0.0.2
 Synopsis:            Library for reading phd sequence files
 Description:         Library for reading phd sequence files
 Homepage:	     https://patch-tag.com/r/dfornika/biophd/home
@@ -14,7 +14,7 @@
 
 Library
   Build-depends:     base >= 2 && < 5, biocore, bytestring, parsec, text, binary
-  Exposed-modules:   Bio.Sequence.Phd
+  Exposed-modules:   Bio.Sequence.Phd, Bio.Sequence.PhdData
   Hs-source-dirs:    src
 
 source-Repository    head
diff --git a/src/Bio/Sequence/PhdData.hs b/src/Bio/Sequence/PhdData.hs
new file mode 100644
--- /dev/null
+++ b/src/Bio/Sequence/PhdData.hs
@@ -0,0 +1,101 @@
+module Bio.Sequence.PhdData where
+
+import Bio.Core.Sequence
+import qualified Data.ByteString.Lazy as LB
+import qualified Data.ByteString.Lazy.Char8 as LBC
+
+{-- A .phd file consists of a DNA block with base and quality 
+    values, followed by one or more (optional) tag blocks. --}
+data PHD = PHD Comment DNABlock (Maybe [PhdTag]) deriving (Show)
+
+{-- These types are subject to change if it improves functionality,
+    but for now it's simplest to just call them String, Int etc.--}
+data Comment = Comment
+    { chromatFile        :: FilePath
+    , abiThumbprint      :: String
+    , phredVersion       :: String
+    , callMethod         :: String
+    , qualityLevels      :: Int
+    , time               :: String
+    , traceArrayMinIndex :: Int
+    , traceArrayMaxIndex :: Int
+    , trim               :: String
+    , chem               :: String
+    , dye                :: String
+    } deriving (Eq)
+
+instance Show Comment where
+    show (Comment cf abit pv cm ql ti mintai maxtai tr ch dy) =
+      ("\n" ++) $ unlines 
+                    [ "CHROMAT_FILE: "   ++ cf
+                    , "ABI_THUMBPRINT: " ++ abit
+                    , "PHRED_VERSION: "  ++ pv 
+                    , "CALL_METHOD: "    ++ cm
+                    , "QUALITY_LEVELS: " ++ show ql 
+                    , "TIME: "           ++ show ti
+                    , "TRACE_ARRAY_MIN_INDEX: " ++ show mintai
+                    , "TRACE_ARRAY_MAX_INDEX: " ++ show maxtai
+                    , "TRIM: "           ++ tr
+                    , "CHEM: "           ++ ch
+                    , "DYE: "            ++ dy
+                    ]
+
+data DNABlock = DNABlock
+    { label        :: String
+    , bases        :: SeqData
+    , qualities    :: QualData
+    , traceIndices :: [Int]
+    }
+
+instance Show DNABlock where
+  show = LBC.unpack . toFasta
+
+data PhdTag = PhdTag
+    { tagType              :: String
+    , source               :: String
+    , unpaddedReadPosition :: [Offset]
+    , date                 :: String
+    , comment              :: String  
+    } deriving (Eq)
+
+instance Show PhdTag where
+  show (PhdTag tt so urp da co) =
+    ("\n" ++) $ unlines $ map (" " ++)
+      [ "TYPE: "              ++ show tt
+      , "SOURCE: "            ++ show so
+      , "UNPADDED_READ_POS: " ++ show (map unOff urp)
+      , "DATE: "              ++ show da
+      , "COMMENT: "           ++ show co ]
+
+instance BioSeq DNABlock where
+  seqlabel  db = SeqLabel $ LBC.pack $ label db
+  seqdata   db = bases db
+  seqlength db = Offset $ LBC.length $ unSD $ bases db
+
+instance BioSeqQual DNABlock where
+  seqqual = qualities
+
+-- Some default values for the data types, useful for debugging in ghci
+
+defaultComment = Comment { chromatFile        = ""
+                         , abiThumbprint      = "0"
+                         , phredVersion       = "0.980904.e"
+                         , callMethod         = "phred"
+                         , qualityLevels      = 99
+                         , time               = "" 
+                         , traceArrayMinIndex = 0
+                         , traceArrayMaxIndex = 1
+                         , trim               = ""
+                         , chem               = "unknown"
+                         , dye                = "unknown" }
+
+defaultDNABlock = DNABlock { label        = "some_dna"
+                           , bases        = SeqData  $ LBC.pack "aatgcatcta"
+                           , qualities    = QualData $ LBC.pack "0000000000"
+                           , traceIndices = [0,1,2,3,4,5,6,7,8,9,10] }
+
+defaultPhdTag = PhdTag { tagType              = "polymorphism"
+                       , source               = "polyphred"
+                       , unpaddedReadPosition = [5, 5]
+                       , date                 = "01/01/70 00:00:00"
+                       , comment              = "" }