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310 lines
11 KiB
Plaintext
310 lines
11 KiB
Plaintext
About
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-----
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The eReader format has evolved and changed over time. Subsequently, there are
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multiple versions of the eReader format. There are also two different tools
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that can create eReader files. The official tools are Makebook and Dropbook.
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Dropbook is the newer official tool that has replaced Makebook. However,
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Makebook is still in wide use because it supports a wider range of platforms
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than Dropbook. Dropbook is a GUI application that only runs on Windows and
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Apple’s OS X.
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PDB Identiy
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-------
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PNRdPPrs
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202 and 132 headers
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-----------------------------------------
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Older files have a record 0 size of 202 and occasionally 116. Newer files have
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a record 0 size of 132. As of this writing the 202 files only support text and
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images. The image format in the 202 files is the same as the 132 files. The 132
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files support a number of additional features.
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Record 0, eReader header (202)
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------------------
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Note all values are in 2 byte increments. Like values are condensed into a
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range. The range can be borken into 2 byte sections which represent the actual
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stored values.
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bytes content comments
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0-2 Version Non-DRM books 2 and 4.
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2-8 Garbage
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8-10 Non-Text Offset Start of Non text area (images) will run to the
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end of the section list.
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10-14 Unknown
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14-24 Garbage
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24-28 Unknown
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28-98 Garbage
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98-100 Unknown
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100-110 Garbage
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110-114 Unknown
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114-116 Garbage
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116-202 Unknown
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* Garbage: Intentially random values.
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Text Records (202)
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------------------
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Text starts with section 1 and continues until the section indicated by the
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Non-Text Offset. All text records are PalmDoc compressed.
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Each character in the compressed data is xored with 0xA5.
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A decompression example in sudo Python:
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for num in range(1, Non-Text Offset):
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text += decompress_pamldoc(''.join([chr(ord(x) ^ 0xA5) for x in section_data(num)])).decode('cp1252', 'replace')
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Dropbook 132 files
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------------------
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The following sections apply to the newer Dropbook created files.
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Record 0, eReader header (132)
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----------------------------
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This is only for 132 byte header files created by Dropbook.
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bytes content comments
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0-2 compression Specifies compression and drm. 2 = palmdoc,
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10 = zlib. 260 and 272 = DRM
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2-6 unknown Value of 0 is used
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6-8 encoding Always 25152 (0x6240). All text must be
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encoded as Latin-1 cp1252
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8-10 Number of small pages The number of small font pages. If page
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index is not build in then 0.
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10-12 Number of large pages The number of large font pages. If page
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index is not build in then 0.
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12-14 Non-Text record start The location of the first non text records.
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record 1 to this value minus 1 are all text
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records
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14-16 Number of chapters The number of chapter index records
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contained in the file
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16-18 Number of small index The number of small font page index records
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contained in the file
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18-20 Number of large index The number of large font page index records
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contained in the file
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20-22 Number of images The number of images contained in the file
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22-24 Number of links The number of links contained in the file
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24-26 Metadata avaliable Is there a metadata record in the file?
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0 = None, 1 = There is a metadata record
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26-28 Unknown Value of 0 is used
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28-30 Number of Footnotes The number of footnote records in the file
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30-32 Number of Sidebars The number of sidebar records in the file
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32-34 Chapter index record start The location of chapter index records. If
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there are no chapters use the value for the
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Last data record.
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34-36 2560 Magic value that must be set to 2560
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36-38 Small page index start The location of small font page index
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records. If page table is not built in use
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the value for the Last data record.
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38-40 Large page index start The location of large font page index
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records. If page table is not built in use
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the value for the Last data record.
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40-42 Image data record start The location of the first image record. If
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there are no images use the value for the
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Last data record.
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42-44 Links record start The location of the first link index
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record. If there are no links use the value
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for the Last data record.
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44-46 Metadata record start The location of the metadata record. If
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there is no metadata use the value for the
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Last data record.
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46-48 Unknown Value of 0 is used
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48-50 Footnote record start The location of the first footnote record.
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If there are no footnotes use the value for
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the Last data record.
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50-52 Sidebar record start The location of the first sidebar record.
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If there are no sidebars use the value for
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the Last data record.
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52-54 Last data record The location of the last data record
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54-132 Unknown Value of 0 is used
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Note: All values are in 2 byte increments. All bytes in the table that have a
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range larger than 2 can be broken into 2 byte segments and have different
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values set for each grouping.
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Records Order
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-------------
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Though the order of this sections is described in eReader header,
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DropBook makes the following order:
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1. eReader Header
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2. Compressed text
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3. Small font page index
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4. Large font page index
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5. Chapter index
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6. Links index
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7. Images
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8. (Extrapolation: there should be one more record type here though it has
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not yet been uncovered what it might be).
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9. Metadata
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10. Sidebar records
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11. Footnote records
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12. Text block size record
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13. "MeTaInFo\x00" word record
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Text Records
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------------
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All text records use cp1252 encoding (although eReader documents talk about
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UTF-8 as well). Their total compressed size is unknown however, anything below
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3560 Bytes is known to work. The text will be either zlib or palmdoc
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compressed. Use the compression value from the eReader header to determine
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which. All text utalizes the Palm Markup Language (PML) for formatting.
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Starting with DropBook 1.6.0 text is divided into 8KB (8192 bytes) blocks
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trimming the end to the closest space character and then being compressed.
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Earlier version of DropBook 1.5.2 tries to behave the same way, though
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sometimes it trims the block in unexpected place.
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Chapter Index Records
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---------------------
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Each chapter record corresponds to 1 chapter and points at the place in the
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book. Chapter record takes a form of 'offset name\x00' First 4 bytes are offset
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of the original pml file where the chapter index points to (offset of
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the \x|\X?|\C? tags). Then without a space goes a name of a chapter in chapter
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index. It should contain only text, all formatting tags should be removed.
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\U and \a tags are not permitted in chapter name. To maintain sub-chapters
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4*n spaces (\x20) are added to the beginning of the name, where "n" is level of
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chapter: 0 for \x tag and N for \CN="" and \XN tags. And then an ending
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\x00 symbol.
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Image Records
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-------------
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Image records must be smaller than 65505 Bytes. They must also be 8bit PNG
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images.
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An image record takes the form 'PNG name\x00... image_data'
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bytes content comments
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0-4 PNG There must be a space after PNG.
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4-36 image name. The image name must be 32 exactly 32 Bytes long. Pad
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the right side of the name with \x00 characters for
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names shorter than 32 characters.
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36-58 Unknown
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58-60 width Width of an image
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60-62 height Height of an image
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62-? The image data raw image data in 8 bit PNG format
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Note: DropBooks seems to change something in png raw data. Like reencoding or
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something, but plain insertion of png image there still works.
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Links Records
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-------------
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Links records are constructed the same way as chapter ones. Each link anchor
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record corresponds to 1 link anchor and points at the place in the book. Link
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record takes a form of 'offset name\x00' First 4 bytes are offset of the
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original pml file where the link anchor points to (offset of the \Q tag). Then
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without a space goes a name of a link anchor. It should contain only text, all
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formatting tags should be removed. \U and \a tags are not permitted in link
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anchor name. And then an ending \x00 symbol.
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Footnote Records
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----------------
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The first footnote record is a \x00 separated list of footnote ids. All
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subsequent footnote records are the footnote text corresponding to the id's
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position in the list. Footnote text is compressed in the same manner as normal
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text records
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E.G.
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footnote section 1 = 'notice1\x00notice2\x00notice3\x00'
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footnote section 2 = 'Text for notice 1'
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footnote section 3 = 'Text for notice 2'
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footnote section 4 = 'Text for notice 3'
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Starting with Dropbook 1.5.2 first record looks a bit different. It is sequence
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of \x00\x01 then 1 byte of footnote id length, then footnote id then \x00.
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E.G.
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footnote section 1 = '\x00\x01\x07notice1\x00\x00\x01\x0Afootnote10\x00'
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Sidebar Records
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---------------
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The first sidebar record is a \x00 separated list of sidebar ids. All
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subsequent sidebar records are the sidebar text corresponding to the id's
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position in the list. Sidebar text is compressed in the same manner as normal
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text records
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E.G.
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sidebar section 1 = 'notice1\x00notice2\x00notice3\x00'
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sidebar section 2 = 'Text for notice 1'
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sidebar section 3 = 'Text for notice 2'
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sidebar section 4 = 'Text for notice 3'
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Starting with Dropbook 1.5.2 first record looks a bit different. It is sequence
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of \x00\x01 then 1 byte of sidebar's id length, then sidebar's id then \x00.
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E.G.
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sidebar section 1 = '\x00\x01\x07notice1\x00\x00\x01\x09sidebar10\x00'
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Metadata Record
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---------------
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\x00 separated list of string.
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Metadata takes the form:
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title\x00
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author\x00
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copyright\x00
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publisher\x00
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isbn\x00
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E.G.
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Gibraltar Earth\x00Michael McCollum\x001999\x00Sci Fi Arizona\x001929381255\x00
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The metdata record is always followed by a record which contains 'MeTaInFo\x00'
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Note: Starting with DropBook 1.5.2 'MeTaInFo\x00' is not following Metadata
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Record. It is a separate record that ends the file and there are some more
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records between Metadata record and 'MeTaInFo\x00' record.
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Text Sizes Record
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-----------------
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There is a special record that contains the initial size of all text blocks
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before compression. It is just a sequence of 2-byte blocks which are containing
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the sizes.
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E.G.
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\x1F\xFB\x20\x00\x20\x00\x1F\xFE\x1F\xFD\x09\x46
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Note: By this we can judge that theoretical maximum of initial block size is
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65535 bytes.
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