diff --git a/src/calibre/ebooks/mobi/debug/index.py b/src/calibre/ebooks/mobi/debug/index.py
index 6065d12e5e..f005c8b24f 100644
--- a/src/calibre/ebooks/mobi/debug/index.py
+++ b/src/calibre/ebooks/mobi/debug/index.py
@@ -82,6 +82,9 @@ class Index(object):
     def __str__(self):
         return '\n'.join(self.render())
 
+    def __iter__(self):
+        return iter(self.records)
+
 class SKELIndex(Index):
 
     def __init__(self, skelidx, records, codec):
diff --git a/src/calibre/ebooks/mobi/debug/mobi8.py b/src/calibre/ebooks/mobi/debug/mobi8.py
index 21ed11fc51..c5cd8d2d69 100644
--- a/src/calibre/ebooks/mobi/debug/mobi8.py
+++ b/src/calibre/ebooks/mobi/debug/mobi8.py
@@ -14,7 +14,7 @@ from calibre import CurrentDir
 from calibre.ebooks.mobi.debug.headers import TextRecord
 from calibre.ebooks.mobi.debug.index import (SKELIndex, SECTIndex, NCXIndex,
         GuideIndex)
-from calibre.ebooks.mobi.utils import read_font_record
+from calibre.ebooks.mobi.utils import read_font_record, decode_tbs
 from calibre.ebooks.mobi.debug import format_bytes
 from calibre.ebooks.mobi.reader.headers import NULL_INDEX
 
@@ -88,6 +88,7 @@ class MOBIFile(object):
         self.read_fdst()
         self.read_indices()
         self.build_files()
+        self.read_tbs()
 
     def print_header(self, f=sys.stdout):
         print (str(self.mf.palmdb).encode('utf-8'), file=f)
@@ -183,6 +184,45 @@ class MOBIFile(object):
             self.resource_map.append(('%s/%06d%s.%s'%(prefix, i, suffix, ext),
                 payload))
 
+    def read_tbs(self):
+        from calibre.ebooks.mobi.writer8.tbs import (Entry,
+                collect_indexing_data)
+        entry_map = []
+        for index in self.ncx_index:
+            enders = [e['pos'] for e in self.ncx_index if e['pos'] >
+                    index['pos'] and
+                    e['hlvl'] <= index['hlvl']]
+            end = min(enders+[len(self.raw_text)])
+
+            entry_map.append(Entry(index=index['num'], title=index['text'],
+                depth=index['hlvl'],
+                parent=index['parent'] if index['parent'] > -1 else None,
+                first_child=index['child1'] if index['child1'] > -1 else None,
+                last_child=index['childn'] if index['childn'] > -1 else None,
+                start=index['pos'], length=end-index['pos']))
+
+        indexing_data = collect_indexing_data(entry_map,
+                len(self.text_records))
+        self.indexing_data = []
+        for i, data in enumerate(indexing_data):
+            rec = self.text_records[i]
+            tbs_bytes = rec.trailing_data.get('indexing', b'')
+            desc = ['Record #%d'%i]
+            for x in ('starts', 'completes', 'ends', 'spans'):
+                points = ['\t%d at depth: %d'%(e.index, e.depth) for e in
+                    getattr(data, x)]
+                if points:
+                    desc.append(x+':')
+                    desc.extend(points)
+            desc.append('TBS Bytes: ' + format_bytes(tbs_bytes))
+            val, extra, consumed = decode_tbs(tbs_bytes, flag_size=3)
+            extra = {bin(k):v for k, v in extra.iteritems()}
+            desc.append('First sequence: %r %r'%(val, extra))
+            byts = tbs_bytes[consumed:]
+            if byts:
+                desc.append('Remaining bytes: %s'%format_bytes(byts))
+            desc.append('')
+            self.indexing_data.append('\n'.join(desc))
 
 def inspect_mobi(mobi_file, ddir):
     f = MOBIFile(mobi_file)
@@ -193,7 +233,8 @@ def inspect_mobi(mobi_file, ddir):
     with open(alltext, 'wb') as of:
         of.write(f.raw_text)
 
-    for x in ('text_records', 'images', 'fonts', 'binary', 'files', 'flows'):
+    for x in ('text_records', 'images', 'fonts', 'binary', 'files', 'flows',
+            'tbs'):
         os.mkdir(os.path.join(ddir, x))
 
     for rec in f.text_records:
@@ -219,6 +260,8 @@ def inspect_mobi(mobi_file, ddir):
     with open(os.path.join(ddir, 'guide.record'), 'wb') as fo:
         fo.write(str(f.guide_index).encode('utf-8'))
 
+    with open(os.path.join(ddir, 'tbs', 'all.txt'), 'wb') as fo:
+        fo.write(('\n'.join(f.indexing_data)).encode('utf-8'))
 
     for part in f.files:
         part.dump(os.path.join(ddir, 'files'))
diff --git a/src/calibre/ebooks/mobi/writer2/main.py b/src/calibre/ebooks/mobi/writer2/main.py
index f064fd2625..4737224336 100644
--- a/src/calibre/ebooks/mobi/writer2/main.py
+++ b/src/calibre/ebooks/mobi/writer2/main.py
@@ -397,7 +397,10 @@ class MobiWriter(object):
         header_fields['exth_flags'] = 0b100001010000 # Kinglegen uses this
         header_fields['fdst_record'] = NULL_INDEX
         header_fields['fdst_count'] = 1 # Why not 0? Kindlegen uses 1
-        header_fields['extra_data_flags'] = 0b11
+        extra_data_flags = 0b1 # Has multibyte overlap bytes
+        if self.primary_index_record_idx is not None:
+            extra_data_flags |= 0b10
+        header_fields['extra_data_flags'] = extra_data_flags
 
         for k, v in {'last_text_record':'last_text_record_idx',
                 'first_non_text_record':'first_non_text_record_idx',
diff --git a/src/calibre/ebooks/mobi/writer8/main.py b/src/calibre/ebooks/mobi/writer8/main.py
index 5e2c75b267..ef34692fd3 100644
--- a/src/calibre/ebooks/mobi/writer8/main.py
+++ b/src/calibre/ebooks/mobi/writer8/main.py
@@ -27,6 +27,7 @@ from calibre.ebooks.mobi.writer8.skeleton import Chunker, aid_able_tags, to_href
 from calibre.ebooks.mobi.writer8.index import (NCXIndex, SkelIndex,
         ChunkIndex, GuideIndex)
 from calibre.ebooks.mobi.writer8.mobi import KF8Book
+from calibre.ebooks.mobi.writer8.tbs import apply_trailing_byte_sequences
 
 XML_DOCS = OEB_DOCS | {SVG_MIME}
 
@@ -39,6 +40,7 @@ class KF8Writer(object):
     def __init__(self, oeb, opts, resources):
         self.oeb, self.opts, self.log = oeb, opts, oeb.log
         self.compress = not self.opts.dont_compress
+        self.has_tbs = False
         self.log.info('Creating KF8 output')
         self.used_images = set()
         self.resources = resources
@@ -363,6 +365,8 @@ class KF8Writer(object):
         for entry in entries:
             entry['length'] = get_next_start(entry) - entry['offset']
 
+        self.has_tbs = apply_trailing_byte_sequences(entries, self.records,
+                self.last_text_record_idx+1)
         self.ncx_records = NCXIndex(entries)()
 
     def create_guide(self):
diff --git a/src/calibre/ebooks/mobi/writer8/mobi.py b/src/calibre/ebooks/mobi/writer8/mobi.py
index ff096f350b..7cdfd5a4b1 100644
--- a/src/calibre/ebooks/mobi/writer8/mobi.py
+++ b/src/calibre/ebooks/mobi/writer8/mobi.py
@@ -250,6 +250,8 @@ class KF8Book(object):
         self.full_title = utf8_text(unicode(metadata.title[0]))
         self.title_length = len(self.full_title)
         self.extra_data_flags = 0b1
+        if writer.has_tbs:
+            self.extra_data_flags |= 0b10
         self.uid = random.randint(0, 0xffffffff)
 
         self.language_code = iana2mobi(str(metadata.language[0]))
diff --git a/src/calibre/ebooks/mobi/writer8/tbs.py b/src/calibre/ebooks/mobi/writer8/tbs.py
new file mode 100644
index 0000000000..36ecdcdf5c
--- /dev/null
+++ b/src/calibre/ebooks/mobi/writer8/tbs.py
@@ -0,0 +1,109 @@
+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__   = 'GPL v3'
+__copyright__ = '2012, Kovid Goyal <kovid@kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+from collections import namedtuple
+from functools import partial
+
+from calibre.ebooks.mobi.utils import (RECORD_SIZE, encode_trailing_data,
+        encode_tbs)
+
+Entry = namedtuple('IndexEntry', 'index start length depth parent '
+        'first_child last_child title')
+Data = namedtuple('Data', 'starts ends completes spans')
+
+def collect_indexing_data(entries, number_of_text_records):
+    ''' For every text record calculate which index entries start, end, span or
+    are contained within that record.'''
+
+    data = []
+    for i in xrange(number_of_text_records):
+        record_start, next_record_start = i*RECORD_SIZE, (i+1)*RECORD_SIZE
+        datum = Data([], [], [], [])
+        data.append(datum)
+
+        for entry in entries:
+            end = entry.start + entry.length - 1
+            if (entry.start >= next_record_start or end < record_start):
+                # This entry does not have any overlap with this record
+                continue
+            if (entry.start < record_start and end >= next_record_start):
+                # This entry spans this record
+                datum.spans.append(entry)
+                continue
+            if (entry.start >= record_start and end < next_record_start):
+                # This entry is contained in this record
+                datum.completes.append(entry)
+            if (entry.start >= record_start and end >= next_record_start):
+                # This entry starts in this record
+                datum.starts.append(entry)
+                continue
+            if (entry.start < record_start and end < next_record_start):
+                # This entry ends in this record
+                datum.ends.append(entry)
+
+        for x in datum:
+            # Should be unnecessary as entries are already in this order, but
+            # best to be safe.
+            x.sort(key=lambda x:x.depth)
+
+    return data
+
+def generate_tbs_for_flat_index(indexing_data):
+    ans = []
+    record_type = 8 # 8 for KF8 0 for MOBI 6
+    enc = partial(encode_tbs, flag_size=3)
+    for datum in indexing_data:
+        tbs = b''
+        extra = {0b010 : record_type}
+        if not (datum.starts or datum.ends or datum.completes or datum.spans):
+            # No index entry touches this record
+            pass
+        elif datum.spans:
+            extra[0b001] = 0
+            tbs = enc(datum.spans[0].index, extra)
+        else:
+            starts, ends, completes = datum[:3]
+            if (not completes and len(starts) + len(ends) == 1):
+                # Either has the first or the last index, and no other indices.
+                node = (starts+ends)[0]
+                tbs = enc(node.index, extra)
+            else:
+                # This record contains the end of an index and
+                # some complete index entries. Or it contains some complete
+                # entries and a start. Or it contains an end, a start and
+                # optionally some completes. In every case, we encode the first
+                # entry to touch this record and the number of entries
+                # that touch this record.
+                nodes = starts + completes + ends
+                nodes.sort(key=lambda x:x.index)
+                extra[0b100] = len(nodes)
+                tbs = enc(nodes[0].index, extra)
+        ans.append(tbs)
+
+    return ans
+
+def apply_trailing_byte_sequences(index_table, records, number_of_text_records):
+    entries = tuple(Entry(r['index'], r['offset'], r['length'], r['depth'],
+        r.get('parent', None), r.get('first_child', None), r.get('last_child',
+            None), r['label']) for r in index_table)
+
+    indexing_data = collect_indexing_data(entries, number_of_text_records)
+    max_depth = max(e['depth'] for e in index_table)
+    if max_depth > 0:
+        # TODO: Implement for hierarchical ToCs
+        tbs = []
+    else:
+        tbs = generate_tbs_for_flat_index(indexing_data)
+    if not tbs:
+        return False
+    for i, tbs_bytes in enumerate(tbs):
+        records[i+1] += encode_trailing_data(tbs_bytes)
+    return True
+
+