diff --git a/java/src/com/android/inputmethod/latin/Constants.java b/java/src/com/android/inputmethod/latin/Constants.java
index c4f9601..9a96530 100644
--- a/java/src/com/android/inputmethod/latin/Constants.java
+++ b/java/src/com/android/inputmethod/latin/Constants.java
@@ -174,6 +174,7 @@
     public static final int CODE_SLASH = '/';
     public static final int CODE_COMMERCIAL_AT = '@';
     public static final int CODE_PLUS = '+';
+    public static final int CODE_PERCENT = '%';
     public static final int CODE_CLOSING_PARENTHESIS = ')';
     public static final int CODE_CLOSING_SQUARE_BRACKET = ']';
     public static final int CODE_CLOSING_CURLY_BRACKET = '}';
diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index b668a77..46b7512 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -1503,6 +1503,7 @@
                 || codePoint == Constants.CODE_CLOSING_CURLY_BRACKET
                 || codePoint == Constants.CODE_CLOSING_ANGLE_BRACKET
                 || codePoint == Constants.CODE_PLUS
+                || codePoint == Constants.CODE_PERCENT
                 || Character.getType(codePoint) == Character.OTHER_SYMBOL;
     }
 
diff --git a/java/src/com/android/inputmethod/latin/makedict/AbstractDictDecoder.java b/java/src/com/android/inputmethod/latin/makedict/AbstractDictDecoder.java
index 9f7f502..fda97da 100644
--- a/java/src/com/android/inputmethod/latin/makedict/AbstractDictDecoder.java
+++ b/java/src/com/android/inputmethod/latin/makedict/AbstractDictDecoder.java
@@ -60,7 +60,8 @@
                         0 != (optionsFlags & FormatSpec.GERMAN_UMLAUT_PROCESSING_FLAG),
                         0 != (optionsFlags & FormatSpec.FRENCH_LIGATURE_PROCESSING_FLAG)),
                         new FormatOptions(version,
-                                0 != (optionsFlags & FormatSpec.SUPPORTS_DYNAMIC_UPDATE)));
+                                0 != (optionsFlags & FormatSpec.SUPPORTS_DYNAMIC_UPDATE),
+                                0 != (optionsFlags & FormatSpec.CONTAINS_TIMESTAMP_FLAG)));
         return header;
     }
 
diff --git a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
index 5a5d7af..605930a 100644
--- a/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
+++ b/java/src/com/android/inputmethod/latin/makedict/FormatSpec.java
@@ -37,13 +37,15 @@
      * sion
      *
      * o |
-     * p | not used                                4 bits
-     * t | has bigrams ?                           1 bit, 1 = yes, 0 = no : CONTAINS_BIGRAMS_FLAG
-     * i | FRENCH_LIGATURE_PROCESSING_FLAG
-     * o | supports dynamic updates ?              1 bit, 1 = yes, 0 = no : SUPPORTS_DYNAMIC_UPDATE
-     * n | GERMAN_UMLAUT_PROCESSING_FLAG
-     * f |
-     * lags
+     * p | not used                                3 bits
+     * t | each unigram and bigram entry has a time stamp?
+     * i |                                         1 bit, 1 = yes, 0 = no : CONTAINS_TIMESTAMP_FLAG
+     * o | has bigrams ?                           1 bit, 1 = yes, 0 = no : CONTAINS_BIGRAMS_FLAG
+     * n | FRENCH_LIGATURE_PROCESSING_FLAG
+     * f | supports dynamic updates ?              1 bit, 1 = yes, 0 = no : SUPPORTS_DYNAMIC_UPDATE
+     * l | GERMAN_UMLAUT_PROCESSING_FLAG
+     * a |
+     * gs
      *
      * h |
      * e | size of the file header, 4bytes
@@ -211,6 +213,8 @@
     static final int SUPPORTS_DYNAMIC_UPDATE = 0x2;
     static final int FRENCH_LIGATURE_PROCESSING_FLAG = 0x4;
     static final int CONTAINS_BIGRAMS_FLAG = 0x8;
+    // TODO: Implement timestamps for unigram.
+    static final int CONTAINS_TIMESTAMP_FLAG = 0x10;
 
     // TODO: Make this value adaptative to content data, store it in the header, and
     // use it in the reading code.
@@ -276,9 +280,14 @@
     // is 584KB with the block size being 4.
     // This is 91% of that of full address table.
     static final int BIGRAM_ADDRESS_TABLE_BLOCK_SIZE = 4;
-    static final int BIGRAM_CONTENT_COUNT = 1;
+    static final int BIGRAM_CONTENT_COUNT = 2;
     static final int BIGRAM_FREQ_CONTENT_INDEX = 0;
+    static final int BIGRAM_TIMESTAMP_CONTENT_INDEX = 1;
     static final String BIGRAM_FREQ_CONTENT_ID = "_freq";
+    static final String BIGRAM_TIMESTAMP_CONTENT_ID = "_timestamp";
+    static final int BIGRAM_TIMESTAMP_SIZE = 4;
+    static final int BIGRAM_COUNTER_SIZE = 1;
+    static final int BIGRAM_LEVEL_SIZE = 1;
 
     static final int SHORTCUT_CONTENT_COUNT = 1;
     static final int SHORTCUT_CONTENT_INDEX = 0;
@@ -321,6 +330,7 @@
         public final int mVersion;
         public final boolean mSupportsDynamicUpdate;
         public final boolean mHasTerminalId;
+        public final boolean mHasTimestamp;
         @UsedForTesting
         public FormatOptions(final int version) {
             this(version, false);
@@ -328,6 +338,11 @@
 
         @UsedForTesting
         public FormatOptions(final int version, final boolean supportsDynamicUpdate) {
+            this(version, supportsDynamicUpdate, false /* hasTimestamp */);
+        }
+
+        public FormatOptions(final int version, final boolean supportsDynamicUpdate,
+                final boolean hasTimestamp) {
             mVersion = version;
             if (version < FIRST_VERSION_WITH_DYNAMIC_UPDATE && supportsDynamicUpdate) {
                 throw new RuntimeException("Dynamic updates are only supported with versions "
@@ -335,6 +350,7 @@
             }
             mSupportsDynamicUpdate = supportsDynamicUpdate;
             mHasTerminalId = (version >= FIRST_VERSION_WITH_TERMINAL_ID);
+            mHasTimestamp = hasTimestamp;
         }
     }
 
diff --git a/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java b/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java
index 5372907..734223e 100644
--- a/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java
+++ b/java/src/com/android/inputmethod/latin/makedict/Ver4DictDecoder.java
@@ -153,8 +153,12 @@
         final File contentFile = new File(mDictDirectory, mDictDirectory.getName()
                 + FormatSpec.SHORTCUT_FILE_EXTENSION + FormatSpec.CONTENT_TABLE_FILE_SUFFIX
                 + FormatSpec.SHORTCUT_CONTENT_ID);
+        final File timestampsFile = new File(mDictDirectory, mDictDirectory.getName()
+                + FormatSpec.SHORTCUT_FILE_EXTENSION + FormatSpec.CONTENT_TABLE_FILE_SUFFIX
+                + FormatSpec.SHORTCUT_CONTENT_ID);
         mShortcutAddressTable = SparseTable.readFromFiles(lookupIndexFile,
-                new File[] { contentFile }, FormatSpec.SHORTCUT_ADDRESS_TABLE_BLOCK_SIZE);
+                new File[] { contentFile, timestampsFile },
+                FormatSpec.SHORTCUT_ADDRESS_TABLE_BLOCK_SIZE);
     }
 
     protected static class PtNodeReader extends AbstractDictDecoder.PtNodeReader {
diff --git a/java/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java b/java/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java
index f9dcacf..fe98942 100644
--- a/java/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java
+++ b/java/src/com/android/inputmethod/latin/makedict/Ver4DictEncoder.java
@@ -69,16 +69,16 @@
         private final File[] mContentFiles;
         protected final OutputStream[] mContentOutStreams;
 
-        public SparseTableContentWriter(final String name, final int contentCount,
-                final int initialCapacity, final int blockSize, final File baseDir,
-                final String[] contentFilenames, final String[] contentIds) {
+        public SparseTableContentWriter(final String name, final int initialCapacity,
+                final int blockSize, final File baseDir, final String[] contentFilenames,
+                final String[] contentIds) {
             if (contentFilenames.length != contentIds.length) {
                 throw new RuntimeException("The length of contentFilenames and the length of"
                         + " contentIds are different " + contentFilenames.length + ", "
                         + contentIds.length);
             }
-            mContentCount = contentCount;
-            mSparseTable = new SparseTable(initialCapacity, blockSize, contentCount);
+            mContentCount = contentFilenames.length;
+            mSparseTable = new SparseTable(initialCapacity, blockSize, mContentCount);
             mLookupTableFile = new File(baseDir, name + FormatSpec.LOOKUP_TABLE_FILE_SUFFIX);
             mAddressTableFiles = new File[mContentCount];
             mContentFiles = new File[mContentCount];
@@ -113,16 +113,40 @@
     }
 
     private static class BigramContentWriter extends SparseTableContentWriter {
+        private final boolean mWriteTimestamp;
 
         public BigramContentWriter(final String name, final int initialCapacity,
-                final File baseDir) {
-            super(name + FormatSpec.BIGRAM_FILE_EXTENSION, FormatSpec.BIGRAM_CONTENT_COUNT,
-                    initialCapacity, FormatSpec.BIGRAM_ADDRESS_TABLE_BLOCK_SIZE, baseDir,
-                    new String[] { name + FormatSpec.BIGRAM_FILE_EXTENSION },
-                    new String[] { FormatSpec.BIGRAM_FREQ_CONTENT_ID });
+                final File baseDir, final boolean writeTimestamp) {
+            super(name + FormatSpec.BIGRAM_FILE_EXTENSION, initialCapacity,
+                    FormatSpec.BIGRAM_ADDRESS_TABLE_BLOCK_SIZE, baseDir,
+                    getContentFilenames(name, writeTimestamp), getContentIds(writeTimestamp));
+            mWriteTimestamp = writeTimestamp;
         }
 
-        public void writeBigramsForOneWord(final int terminalId,
+        private static String[] getContentFilenames(final String name,
+                final boolean writeTimestamp) {
+            final String[] contentFilenames;
+            if (writeTimestamp) {
+                contentFilenames = new String[] { name + FormatSpec.BIGRAM_FILE_EXTENSION,
+                        name + FormatSpec.BIGRAM_FILE_EXTENSION };
+            } else {
+                contentFilenames = new String[] { name + FormatSpec.BIGRAM_FILE_EXTENSION };
+            }
+            return contentFilenames;
+        }
+
+        private static String[] getContentIds(final boolean writeTimestamp) {
+            final String[] contentIds;
+            if (writeTimestamp) {
+                contentIds = new String[] { FormatSpec.BIGRAM_FREQ_CONTENT_ID,
+                        FormatSpec.BIGRAM_TIMESTAMP_CONTENT_ID };
+            } else {
+                contentIds = new String[] { FormatSpec.BIGRAM_FREQ_CONTENT_ID };
+            }
+            return contentIds;
+        }
+
+        public void writeBigramsForOneWord(final int terminalId, final int bigramCount,
                 final Iterator<WeightedString> bigramIterator, final FusionDictionary dict)
                         throws IOException {
             write(FormatSpec.BIGRAM_FREQ_CONTENT_INDEX, terminalId,
@@ -130,8 +154,16 @@
                         @Override
                         public void write(final OutputStream outStream) throws IOException {
                             writeBigramsForOneWordInternal(outStream, bigramIterator, dict);
-                        }
-            });
+                        }});
+            if (mWriteTimestamp) {
+                write(FormatSpec.BIGRAM_TIMESTAMP_CONTENT_INDEX, terminalId,
+                        new SparseTableContentWriterInterface() {
+                            @Override
+                            public void write(final OutputStream outStream) throws IOException {
+                                initBigramTimestampsCountersAndLevelsForOneWordInternal(outStream,
+                                        bigramCount);
+                            }});
+            }
         }
 
         private void writeBigramsForOneWordInternal(final OutputStream outStream,
@@ -151,13 +183,26 @@
                         FormatSpec.PTNODE_ATTRIBUTE_MAX_ADDRESS_SIZE);
             }
         }
+
+        private void initBigramTimestampsCountersAndLevelsForOneWordInternal(
+                final OutputStream outStream, final int bigramCount) throws IOException {
+            for (int i = 0; i < bigramCount; ++i) {
+                // TODO: Figure out what initial values should be.
+                BinaryDictEncoderUtils.writeUIntToStream(outStream, 0 /* value */,
+                        FormatSpec.BIGRAM_TIMESTAMP_SIZE);
+                BinaryDictEncoderUtils.writeUIntToStream(outStream, 0 /* value */,
+                        FormatSpec.BIGRAM_COUNTER_SIZE);
+                BinaryDictEncoderUtils.writeUIntToStream(outStream, 0 /* value */,
+                        FormatSpec.BIGRAM_LEVEL_SIZE);
+            }
+        }
     }
 
     private static class ShortcutContentWriter extends SparseTableContentWriter {
         public ShortcutContentWriter(final String name, final int initialCapacity,
                 final File baseDir) {
-            super(name + FormatSpec.SHORTCUT_FILE_EXTENSION, FormatSpec.SHORTCUT_CONTENT_COUNT,
-                    initialCapacity, FormatSpec.SHORTCUT_ADDRESS_TABLE_BLOCK_SIZE, baseDir,
+            super(name + FormatSpec.SHORTCUT_FILE_EXTENSION, initialCapacity,
+                    FormatSpec.SHORTCUT_ADDRESS_TABLE_BLOCK_SIZE, baseDir,
                     new String[] { name + FormatSpec.SHORTCUT_FILE_EXTENSION },
                     new String[] { FormatSpec.SHORTCUT_CONTENT_ID });
         }
@@ -257,7 +302,8 @@
         if (MakedictLog.DBG) BinaryDictEncoderUtils.checkFlatPtNodeArrayList(flatNodes);
 
         writeTerminalData(flatNodes, terminalCount);
-        mBigramWriter = new BigramContentWriter(mBaseFilename, terminalCount, mDictDir);
+        mBigramWriter = new BigramContentWriter(mBaseFilename, terminalCount, mDictDir,
+                formatOptions.mHasTimestamp);
         writeBigrams(flatNodes, dict);
         mShortcutWriter = new ShortcutContentWriter(mBaseFilename, terminalCount, mDictDir);
         writeShortcuts(flatNodes);
@@ -348,7 +394,7 @@
         for (final PtNodeArray nodeArray : flatNodes) {
             for (final PtNode ptNode : nodeArray.mData) {
                 if (ptNode.mBigrams != null) {
-                    mBigramWriter.writeBigramsForOneWord(ptNode.mTerminalId,
+                    mBigramWriter.writeBigramsForOneWord(ptNode.mTerminalId, ptNode.mBigrams.size(),
                             ptNode.mBigrams.iterator(), dict);
                 }
             }
diff --git a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
index 0189b33..32c07e1 100644
--- a/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
+++ b/tests/src/com/android/inputmethod/latin/makedict/BinaryDictDecoderEncoderTests.java
@@ -80,6 +80,9 @@
             new FormatSpec.FormatOptions(4, false /* supportsDynamicUpdate */);
     private static final FormatSpec.FormatOptions VERSION4_WITH_DYNAMIC_UPDATE =
             new FormatSpec.FormatOptions(4, true /* supportsDynamicUpdate */);
+    private static final FormatSpec.FormatOptions VERSION4_WITH_DYNAMIC_UPDATE_AND_TIMESTAMP =
+            new FormatSpec.FormatOptions(4, true /* supportsDynamicUpdate */,
+                    true /* hasTimestamp */);
 
     private static final String TEST_DICT_FILE_EXTENSION = ".testDict";
 
@@ -363,6 +366,7 @@
         runReadAndWriteTests(results, USE_BYTE_BUFFER, VERSION3_WITH_DYNAMIC_UPDATE);
         runReadAndWriteTests(results, USE_BYTE_BUFFER, VERSION4_WITHOUT_DYNAMIC_UPDATE);
         runReadAndWriteTests(results, USE_BYTE_BUFFER, VERSION4_WITH_DYNAMIC_UPDATE);
+        runReadAndWriteTests(results, USE_BYTE_BUFFER, VERSION4_WITH_DYNAMIC_UPDATE_AND_TIMESTAMP);
 
         for (final String result : results) {
             Log.d(TAG, result);
@@ -377,6 +381,7 @@
         runReadAndWriteTests(results, USE_BYTE_ARRAY, VERSION3_WITH_DYNAMIC_UPDATE);
         runReadAndWriteTests(results, USE_BYTE_ARRAY, VERSION4_WITHOUT_DYNAMIC_UPDATE);
         runReadAndWriteTests(results, USE_BYTE_ARRAY, VERSION4_WITH_DYNAMIC_UPDATE);
+        runReadAndWriteTests(results, USE_BYTE_ARRAY, VERSION4_WITH_DYNAMIC_UPDATE_AND_TIMESTAMP);
 
         for (final String result : results) {
             Log.d(TAG, result);
@@ -508,6 +513,8 @@
         runReadUnigramsAndBigramsTests(results, USE_BYTE_BUFFER, VERSION3_WITH_DYNAMIC_UPDATE);
         runReadUnigramsAndBigramsTests(results, USE_BYTE_BUFFER, VERSION4_WITHOUT_DYNAMIC_UPDATE);
         runReadUnigramsAndBigramsTests(results, USE_BYTE_BUFFER, VERSION4_WITH_DYNAMIC_UPDATE);
+        runReadUnigramsAndBigramsTests(results, USE_BYTE_BUFFER,
+                VERSION4_WITH_DYNAMIC_UPDATE_AND_TIMESTAMP);
 
         for (final String result : results) {
             Log.d(TAG, result);
@@ -522,6 +529,8 @@
         runReadUnigramsAndBigramsTests(results, USE_BYTE_ARRAY, VERSION3_WITH_DYNAMIC_UPDATE);
         runReadUnigramsAndBigramsTests(results, USE_BYTE_ARRAY, VERSION4_WITHOUT_DYNAMIC_UPDATE);
         runReadUnigramsAndBigramsTests(results, USE_BYTE_ARRAY, VERSION4_WITH_DYNAMIC_UPDATE);
+        runReadUnigramsAndBigramsTests(results, USE_BYTE_ARRAY,
+                VERSION4_WITH_DYNAMIC_UPDATE_AND_TIMESTAMP);
 
         for (final String result : results) {
             Log.d(TAG, result);
@@ -634,12 +643,14 @@
         runGetTerminalPositionTests(USE_BYTE_ARRAY, VERSION3_WITH_DYNAMIC_UPDATE);
         runGetTerminalPositionTests(USE_BYTE_ARRAY, VERSION4_WITHOUT_DYNAMIC_UPDATE);
         runGetTerminalPositionTests(USE_BYTE_ARRAY, VERSION4_WITH_DYNAMIC_UPDATE);
+        runGetTerminalPositionTests(USE_BYTE_ARRAY, VERSION4_WITH_DYNAMIC_UPDATE_AND_TIMESTAMP);
 
         runGetTerminalPositionTests(USE_BYTE_BUFFER, VERSION2);
         runGetTerminalPositionTests(USE_BYTE_BUFFER, VERSION3_WITHOUT_DYNAMIC_UPDATE);
         runGetTerminalPositionTests(USE_BYTE_BUFFER, VERSION3_WITH_DYNAMIC_UPDATE);
         runGetTerminalPositionTests(USE_BYTE_BUFFER, VERSION4_WITHOUT_DYNAMIC_UPDATE);
         runGetTerminalPositionTests(USE_BYTE_BUFFER, VERSION4_WITH_DYNAMIC_UPDATE);
+        runGetTerminalPositionTests(USE_BYTE_BUFFER, VERSION4_WITH_DYNAMIC_UPDATE_AND_TIMESTAMP);
 
         for (final String result : results) {
             Log.d(TAG, result);