diff --git a/java/src/com/android/inputmethod/latin/makedict/ProbabilityInfo.java b/java/src/com/android/inputmethod/latin/makedict/ProbabilityInfo.java
index d6ce88d..dafbc04 100644
--- a/java/src/com/android/inputmethod/latin/makedict/ProbabilityInfo.java
+++ b/java/src/com/android/inputmethod/latin/makedict/ProbabilityInfo.java
@@ -17,7 +17,7 @@
 package com.android.inputmethod.latin.makedict;
 
 import com.android.inputmethod.latin.BinaryDictionary;
-import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
+import com.android.inputmethod.latin.utils.CombinedFormatUtils;
 
 import java.util.Arrays;
 
@@ -57,8 +57,7 @@
 
     @Override
     public String toString() {
-        return "f=" + mProbability + (hasHistoricalInfo() ?
-                ",historicalInfo=" + mTimestamp + ":" + mLevel + ":" + mCount : "");
+        return CombinedFormatUtils.formatProbabilityInfo(this);
     }
 
     @Override
diff --git a/java/src/com/android/inputmethod/latin/makedict/WordProperty.java b/java/src/com/android/inputmethod/latin/makedict/WordProperty.java
index e764ae3..b93a0a5 100644
--- a/java/src/com/android/inputmethod/latin/makedict/WordProperty.java
+++ b/java/src/com/android/inputmethod/latin/makedict/WordProperty.java
@@ -20,6 +20,7 @@
 import com.android.inputmethod.latin.BinaryDictionary;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
 import com.android.inputmethod.latin.utils.CollectionUtils;
+import com.android.inputmethod.latin.utils.CombinedFormatUtils;
 import com.android.inputmethod.latin.utils.StringUtils;
 
 import java.util.ArrayList;
@@ -52,8 +53,8 @@
         mBigrams = bigrams;
         mIsNotAWord = isNotAWord;
         mIsBlacklistEntry = isBlacklistEntry;
-        mHasBigrams = !bigrams.isEmpty();
-        mHasShortcuts = !shortcutTargets.isEmpty();
+        mHasBigrams = bigrams != null && !bigrams.isEmpty();
+        mHasShortcuts = shortcutTargets != null && !shortcutTargets.isEmpty();
     }
 
     private static ProbabilityInfo createProbabilityInfoFromArray(final int[] probabilityInfo) {
@@ -158,32 +159,6 @@
 
     @Override
     public String toString() {
-        // TODO: Move this logic to CombinedInputOutput.
-        final StringBuffer builder = new StringBuffer();
-        builder.append(" word=" + mWord);
-        builder.append(",");
-        builder.append(mProbabilityInfo.toString());
-        if (mIsNotAWord) {
-            builder.append(",");
-            builder.append("not_a_word=true");
-        }
-        if (mIsBlacklistEntry) {
-            builder.append(",");
-            builder.append("blacklisted=true");
-        }
-        builder.append("\n");
-        for (int i = 0; i < mBigrams.size(); i++) {
-            builder.append("  bigram=" + mBigrams.get(i).mWord);
-            builder.append(",");
-            builder.append(mBigrams.get(i).mProbabilityInfo.toString());
-            builder.append("\n");
-        }
-        for (int i = 0; i < mShortcutTargets.size(); i++) {
-            builder.append("  shortcut=" + mShortcutTargets.get(i).mWord);
-            builder.append(",");
-            builder.append(mShortcutTargets.get(i).mProbabilityInfo.toString());
-            builder.append("\n");
-        }
-        return builder.toString();
+        return CombinedFormatUtils.formatWordProperty(this);
     }
 }
diff --git a/java/src/com/android/inputmethod/latin/utils/CombinedFormatUtils.java b/java/src/com/android/inputmethod/latin/utils/CombinedFormatUtils.java
new file mode 100644
index 0000000..1348d5e
--- /dev/null
+++ b/java/src/com/android/inputmethod/latin/utils/CombinedFormatUtils.java
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.android.inputmethod.latin.utils;
+
+import com.android.inputmethod.latin.makedict.DictionaryHeader;
+import com.android.inputmethod.latin.makedict.ProbabilityInfo;
+import com.android.inputmethod.latin.makedict.WordProperty;
+import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
+
+import java.util.HashMap;
+
+public class CombinedFormatUtils {
+    public static final String DICTIONARY_TAG = "dictionary";
+    public static final String BIGRAM_TAG = "bigram";
+    public static final String SHORTCUT_TAG = "shortcut";
+    public static final String PROBABILITY_TAG = "f";
+    public static final String HISTORICAL_INFO_TAG = "historicalInfo";
+    public static final String HISTORICAL_INFO_SEPARATOR = ":";
+    public static final String WORD_TAG = "word";
+    public static final String NOT_A_WORD_TAG = "not_a_word";
+    public static final String BLACKLISTED_TAG = "blacklisted";
+
+    public static String formatAttributeMap(final HashMap<String, String> attributeMap) {
+        final StringBuilder builder = new StringBuilder();
+        builder.append(DICTIONARY_TAG + "=");
+        if (attributeMap.containsKey(DictionaryHeader.DICTIONARY_DESCRIPTION_KEY)) {
+            builder.append(attributeMap.get(DictionaryHeader.DICTIONARY_DESCRIPTION_KEY));
+        }
+        for (final String key : attributeMap.keySet()) {
+            if (key == DictionaryHeader.DICTIONARY_DESCRIPTION_KEY) {
+                continue;
+            }
+            final String value = attributeMap.get(key);
+            builder.append("," + key + "=" + value);
+        }
+        builder.append("\n");
+        return builder.toString();
+    }
+
+    public static String formatWordProperty(final WordProperty wordProperty) {
+        final StringBuilder builder = new StringBuilder();
+        builder.append(" " + WORD_TAG + "=" + wordProperty.mWord);
+        builder.append(",");
+        builder.append(formatProbabilityInfo(wordProperty.mProbabilityInfo));
+        if (wordProperty.mIsNotAWord) {
+            builder.append("," + NOT_A_WORD_TAG + "=true");
+        }
+        if (wordProperty.mIsBlacklistEntry) {
+            builder.append("," + BLACKLISTED_TAG + "=true");
+        }
+        builder.append("\n");
+        if (wordProperty.mShortcutTargets != null) {
+            for (final WeightedString shortcutTarget : wordProperty.mShortcutTargets) {
+                builder.append("  " + SHORTCUT_TAG + "=" + shortcutTarget.mWord);
+                builder.append(",");
+                builder.append(formatProbabilityInfo(shortcutTarget.mProbabilityInfo));
+                builder.append("\n");
+            }
+        }
+        if (wordProperty.mBigrams != null) {
+            for (final WeightedString bigram : wordProperty.mBigrams) {
+                builder.append("  " + BIGRAM_TAG + "=" + bigram.mWord);
+                builder.append(",");
+                builder.append(formatProbabilityInfo(bigram.mProbabilityInfo));
+                builder.append("\n");
+            }
+        }
+        return builder.toString();
+    }
+
+    public static String formatProbabilityInfo(final ProbabilityInfo probabilityInfo) {
+        final StringBuilder builder = new StringBuilder();
+        builder.append(PROBABILITY_TAG + "=" + probabilityInfo.mProbability);
+        if (probabilityInfo.hasHistoricalInfo()) {
+            builder.append(",");
+            builder.append(HISTORICAL_INFO_TAG + "=");
+            builder.append(probabilityInfo.mTimestamp);
+            builder.append(HISTORICAL_INFO_SEPARATOR);
+            builder.append(probabilityInfo.mLevel);
+            builder.append(HISTORICAL_INFO_SEPARATOR);
+            builder.append(probabilityInfo.mCount);
+        }
+        return builder.toString();
+    }
+}
diff --git a/tools/dicttool/Android.mk b/tools/dicttool/Android.mk
index 5d1a30e..b83ce57 100644
--- a/tools/dicttool/Android.mk
+++ b/tools/dicttool/Android.mk
@@ -43,6 +43,7 @@
         $(LATINIME_CORE_SOURCE_DIRECTORY)/settings/NativeSuggestOptions.java \
         $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/ByteArrayDictBuffer.java \
         $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/CollectionUtils.java \
+        $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/CombinedFormatUtils.java \
         $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/CoordinateUtils.java \
         $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/FileUtils.java \
         $(LATINIME_CORE_SOURCE_DIRECTORY)/utils/JniUtils.java \
diff --git a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/CombinedInputOutput.java b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/CombinedInputOutput.java
index eae9d9f..8d2f5fb 100644
--- a/tools/dicttool/src/com/android/inputmethod/latin/dicttool/CombinedInputOutput.java
+++ b/tools/dicttool/src/com/android/inputmethod/latin/dicttool/CombinedInputOutput.java
@@ -22,6 +22,7 @@
 import com.android.inputmethod.latin.makedict.FusionDictionary.PtNodeArray;
 import com.android.inputmethod.latin.makedict.FusionDictionary.WeightedString;
 import com.android.inputmethod.latin.makedict.WordProperty;
+import com.android.inputmethod.latin.utils.CombinedFormatUtils;
 
 import java.io.BufferedReader;
 import java.io.File;
@@ -41,16 +42,10 @@
  * All functions in this class are static.
  */
 public class CombinedInputOutput {
-
-    private static final String DICTIONARY_TAG = "dictionary";
-    private static final String BIGRAM_TAG = "bigram";
-    private static final String SHORTCUT_TAG = "shortcut";
-    private static final String PROBABILITY_TAG = "f";
-    private static final String WORD_TAG = "word";
-    private static final String NOT_A_WORD_TAG = "not_a_word";
     private static final String WHITELIST_TAG = "whitelist";
     private static final String OPTIONS_TAG = "options";
     private static final String COMMENT_LINE_STARTER = "#";
+    private static final int HISTORICAL_INFO_ELEMENT_COUNT = 3;
 
     /**
      * Basic test to find out whether the file is in the combined format or not.
@@ -68,7 +63,8 @@
             while (firstLine.startsWith(COMMENT_LINE_STARTER)) {
                 firstLine = reader.readLine();
             }
-            return firstLine.matches("^" + DICTIONARY_TAG + "=[^:]+(:[^=]+=[^:]+)*");
+            return firstLine.matches(
+                    "^" + CombinedFormatUtils.DICTIONARY_TAG + "=[^:]+(:[^=]+=[^:]+)*");
         } catch (FileNotFoundException e) {
             return false;
         } catch (IOException e) {
@@ -123,7 +119,7 @@
         while (null != (line = reader.readLine())) {
             if (line.startsWith(COMMENT_LINE_STARTER)) continue;
             final String args[] = line.trim().split(",");
-            if (args[0].matches(WORD_TAG + "=.*")) {
+            if (args[0].matches(CombinedFormatUtils.WORD_TAG + "=.*")) {
                 if (null != word) {
                     dict.add(word, freq, shortcuts.isEmpty() ? null : shortcuts, isNotAWord);
                     for (WeightedString s : bigrams) {
@@ -136,23 +132,30 @@
                 for (String param : args) {
                     final String params[] = param.split("=", 2);
                     if (2 != params.length) throw new RuntimeException("Wrong format : " + line);
-                    if (WORD_TAG.equals(params[0])) {
+                    if (CombinedFormatUtils.WORD_TAG.equals(params[0])) {
                         word = params[1];
-                    } else if (PROBABILITY_TAG.equals(params[0])) {
+                    } else if (CombinedFormatUtils.PROBABILITY_TAG.equals(params[0])) {
                         freq = Integer.parseInt(params[1]);
-                    } else if (NOT_A_WORD_TAG.equals(params[0])) {
+                    } else if (CombinedFormatUtils.HISTORICAL_INFO_TAG.equals(params[0])) {
+                        final String[] historicalInfoParams =
+                                params[1].split(CombinedFormatUtils.HISTORICAL_INFO_SEPARATOR);
+                        if (historicalInfoParams.length != HISTORICAL_INFO_ELEMENT_COUNT) {
+                            throw new RuntimeException("Wrong format (historical info) : " + line);
+                        }
+                        // TODO: Use parsed historical info.
+                    } else if (CombinedFormatUtils.NOT_A_WORD_TAG.equals(params[0])) {
                         isNotAWord = "true".equals(params[1]);
                     }
                 }
-            } else if (args[0].matches(SHORTCUT_TAG + "=.*")) {
+            } else if (args[0].matches(CombinedFormatUtils.SHORTCUT_TAG + "=.*")) {
                 String shortcut = null;
                 int shortcutFreq = 0;
                 for (String param : args) {
                     final String params[] = param.split("=", 2);
                     if (2 != params.length) throw new RuntimeException("Wrong format : " + line);
-                    if (SHORTCUT_TAG.equals(params[0])) {
+                    if (CombinedFormatUtils.SHORTCUT_TAG.equals(params[0])) {
                         shortcut = params[1];
-                    } else if (PROBABILITY_TAG.equals(params[0])) {
+                    } else if (CombinedFormatUtils.PROBABILITY_TAG.equals(params[0])) {
                         shortcutFreq = WHITELIST_TAG.equals(params[1])
                                 ? FormatSpec.SHORTCUT_WHITELIST_FREQUENCY
                                 : Integer.parseInt(params[1]);
@@ -163,16 +166,23 @@
                 } else {
                     throw new RuntimeException("Wrong format : " + line);
                 }
-            } else if (args[0].matches(BIGRAM_TAG + "=.*")) {
+            } else if (args[0].matches(CombinedFormatUtils.BIGRAM_TAG + "=.*")) {
                 String secondWordOfBigram = null;
                 int bigramFreq = 0;
                 for (String param : args) {
                     final String params[] = param.split("=", 2);
                     if (2 != params.length) throw new RuntimeException("Wrong format : " + line);
-                    if (BIGRAM_TAG.equals(params[0])) {
+                    if (CombinedFormatUtils.BIGRAM_TAG.equals(params[0])) {
                         secondWordOfBigram = params[1];
-                    } else if (PROBABILITY_TAG.equals(params[0])) {
+                    } else if (CombinedFormatUtils.PROBABILITY_TAG.equals(params[0])) {
                         bigramFreq = Integer.parseInt(params[1]);
+                    }  else if (CombinedFormatUtils.HISTORICAL_INFO_TAG.equals(params[0])) {
+                        final String[] historicalInfoParams =
+                                params[1].split(CombinedFormatUtils.HISTORICAL_INFO_SEPARATOR);
+                        if (historicalInfoParams.length != HISTORICAL_INFO_ELEMENT_COUNT) {
+                            throw new RuntimeException("Wrong format (historical info) : " + line);
+                        }
+                        // TODO: Use parsed historical info.
                     }
                 }
                 if (null != secondWordOfBigram) {
@@ -198,40 +208,16 @@
      * @param destination a destination stream to write to.
      * @param dict the dictionary to write.
      */
-    public static void writeDictionaryCombined(Writer destination, FusionDictionary dict)
-            throws IOException {
+    public static void writeDictionaryCombined(
+            final Writer destination, final FusionDictionary dict) throws IOException {
         final TreeSet<WordProperty> wordPropertiesInDict = new TreeSet<WordProperty>();
-        for (WordProperty wordProperty: dict) {
+        for (final WordProperty wordProperty : dict) {
             // This for ordering by frequency, then by asciibetic order
             wordPropertiesInDict.add(wordProperty);
         }
-        final HashMap<String, String> options = dict.mOptions.mAttributes;
-        destination.write(DICTIONARY_TAG + "=");
-        if (options.containsKey(DICTIONARY_TAG)) {
-            destination.write(options.get(DICTIONARY_TAG));
-            options.remove(DICTIONARY_TAG);
-        }
-        for (final String key : dict.mOptions.mAttributes.keySet()) {
-            final String value = dict.mOptions.mAttributes.get(key);
-            destination.write("," + key + "=" + value);
-        }
-        destination.write("\n");
-        for (WordProperty wordProperty : wordPropertiesInDict) {
-            destination.write(" " + WORD_TAG + "=" + wordProperty.mWord + ","
-                    + PROBABILITY_TAG + "=" + wordProperty.getProbability()
-                    + (wordProperty.mIsNotAWord ? "," + NOT_A_WORD_TAG + "=true\n" : "\n"));
-            if (null != wordProperty.mShortcutTargets) {
-                for (WeightedString target : wordProperty.mShortcutTargets) {
-                    destination.write("  " + SHORTCUT_TAG + "=" + target.mWord + ","
-                            + PROBABILITY_TAG + "=" + target.getProbability() + "\n");
-                }
-            }
-            if (null != wordProperty.mBigrams) {
-                for (WeightedString bigram : wordProperty.mBigrams) {
-                    destination.write("  " + BIGRAM_TAG + "=" + bigram.mWord + ","
-                            + PROBABILITY_TAG + "=" + bigram.getProbability() + "\n");
-                }
-            }
+        destination.write(CombinedFormatUtils.formatAttributeMap(dict.mOptions.mAttributes));
+        for (final WordProperty wordProperty : wordPropertiesInDict) {
+            destination.write(CombinedFormatUtils.formatWordProperty(wordProperty));
         }
         destination.close();
     }