diff --git a/src/calibre/devices/hanvon/driver.py b/src/calibre/devices/hanvon/driver.py
index 3ce0fedac0..11b064b783 100644
--- a/src/calibre/devices/hanvon/driver.py
+++ b/src/calibre/devices/hanvon/driver.py
@@ -131,7 +131,7 @@ class AZBOOKA(ALEX):
     description = _('Communicate with the Azbooka')
 
     VENDOR_NAME      = 'LINUX'
-    WINDOWS_MAIN_MEM = 'FILE-STOR_GADGET'
+    WINDOWS_MAIN_MEM = WINDOWS_CARD_A_MEM = 'FILE-STOR_GADGET'
 
     MAIN_MEMORY_VOLUME_LABEL  = 'Azbooka Internal Memory'
 
diff --git a/src/calibre/ebooks/mobi/debug.py b/src/calibre/ebooks/mobi/debug.py
index 32578781b8..8ffa3aa15b 100644
--- a/src/calibre/ebooks/mobi/debug.py
+++ b/src/calibre/ebooks/mobi/debug.py
@@ -574,6 +574,13 @@ class Tag(object): # {{{
 
 class IndexEntry(object): # {{{
 
+    '''
+    The index is made up of entries, each of which is represented by an
+    instance of this class. Index entries typically point to offsets int eh
+    HTML, specify HTML sizes and point to text strings in the CNCX that are
+    used in the navigation UI.
+    '''
+
     TYPES = {
             # Present in book type files
             0x0f : 'chapter',
@@ -619,6 +626,11 @@ class IndexEntry(object): # {{{
 
 class IndexRecord(object): # {{{
 
+    '''
+    Represents all indexing information in the MOBI, apart from indexing info
+    in the trailing data of the text records.
+    '''
+
     def __init__(self, record, index_header, cncx):
         self.record = record
         raw = self.record.raw
@@ -684,6 +696,12 @@ class IndexRecord(object): # {{{
 
 class CNCX(object) : # {{{
 
+    '''
+    Parses the records that contain the compiled NCX (all strings from the
+    NCX). Presents a simple offset : string mapping interface to access the
+    data.
+    '''
+
     def __init__(self, records, codec):
         self.records = OrderedDict()
         pos = 0