221 lines
10 KiB
Plaintext
221 lines
10 KiB
Plaintext
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ARC file header structure
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Byte number Value(s) Meaning
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--------------------------------------------------------------
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0 $1A Header Flag
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1 0-9 Compression method
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2-14 --- Filename.
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15-18 --- Compressed file size.
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19-20 bits Date format
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15-9 Year
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8-5 Month
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4-0 Day
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21-22 bits Time format
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15-11 Hours (military)
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10-5 Minutes
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4-0 Seconds
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23-24 --- CRC-16
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25-28 --- Original file size
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Compression method
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------------------
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1 unpacked (obsolete)
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2 unpacked
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3 packed
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4 squeezed (after packing)
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5 crunched (obsolete)
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6 crunched (after packing) (obsolete)
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7 crunched (after packing, using faster hash algorithm)
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8 crunched (after packing, using dynamic LZW variations)
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9 Squashed c/o Phil Katz (no packing) (var. on crunching)
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NOTE: LZW is Lempel-Ziv-Welch compression algorithm
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LZH
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---
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LZH file header structure
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Byte number Value(s) Meaning
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--------------------------------------------------------------
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0 --- Header size
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1 --- Cksum of remaining bytes
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2-6 --- Method
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7-10 --- Compressed size
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11-14 --- Uncompressed size
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15-16 --- Time format
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17-18 --- Date format
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19-20 --- File attribute
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21-22 --- Filename/path length
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23-XX --- Filename/path
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XX+1-XX+2 --- CRC-16
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Compression method
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------------------
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-lh0- No compression used
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-lh1- LZW, 4K buffer, Huffman for upper 6 bits of pos
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-lz4- LZW, Arithmetic Encoding
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-lz5- LZW, Arithmetic Encoding
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ZIP
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---
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ZIP file header structures
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Local File Header
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-----------------
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Byte number Value(s) Meaning
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--------------------------------------------------------------
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0-3 $04034B50 Local File Header Signature
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4-5 --- Version needed to extract
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6-7 --- General purpose bit flag
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8-9 0-6 Compression method
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10-11 --- Time
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12-13 --- Date
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14-17 --- CRC-32
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18-21 --- Compressed size
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22-25 --- Uncompressed size
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26-27 --- Filename length
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28-29 --- Extra field length
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30-XX --- path/filename
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XX+1-YY --- extra field
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Central Directory Structure
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---------------------------
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Byte number Value(s) Meaning
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--------------------------------------------------------------
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0-3 $02014B50 Central file header signature
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4 --- Version made by
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5 --- Host operating system
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6 --- Version needed to extract
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7 --- O/S of version needed for extraction
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8-9 --- General purpose bit flag
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10-11 0-6 Compression method
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12-13 --- Time
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14-15 --- Date
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16-19 --- CRC-32
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20-23 --- Compressed size
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24-27 --- Uncompressed size
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28-29 --- Filename length
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30-31 --- Extra field length
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32-33 --- File comment length
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34-35 --- Disk number start
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36-37 bit Internal file attributes
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0 if = 1, file is apparently an ASCII
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or text file
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0 if = 0, file apparently contains
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binary data
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1-7 unused in version 1.0.
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38-41 --- External file attributes, host
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system dependent
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42-45 --- Relative offset of local header
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from the start of the first disk
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on which this file appears
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46-XX --- Filename or path - should not
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contain a drive or device letter,
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or a leading slash. All slashes
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should be forward slashes '/'
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XX+1-YY --- extra field
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YY+1-ZZ --- file comment
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End of Central Directory Structure
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----------------------------------
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Byte number Value(s) Meaning
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--------------------------------------------------------------
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0-3 $06064B50 End of central dir signature
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4-5 --- Number of this disk
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6-7 --- Number of disk with start central dir
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8-9 --- Total number of entries in central dir
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on this disk
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10-11 --- total number entries in central dir
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12-15 --- Size of the central directory
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16-19 --- Offset of start of central directory
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with respect to the starting disk
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number
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20-21 --- zipfile comment length
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22-XX --- zipfile comment
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ZIP Values
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----------
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Host O/S
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Value Description Value Description
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----- -------------------------- ----- ------------------------
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0 MS-DOS and OS/2 (FAT) 5 Atari ST
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1 Amiga 6 OS/2 1.2 extended file sys
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2 VMS 7 Macintosh
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3 *nix 8 thru
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4 VM/CMS 255 unused
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General Purpose Bit Flag
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Bit Description
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--------- -----------------------------------------
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0 If set, file is encrypted
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1 If file Imploded and this bit is set, 8K
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sliding dictionary was used. If clear, 4K
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sliding dictionary was used.
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2 If file Imploded and this bit is set, 3
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Shannon-Fano trees were used. If clear, 2
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Shannon-Fano trees were used.
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3-4 unused
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5-7 used internally by ZIP
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Note: Bits 1 and 2 are undefined if the compression method is
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other than type 6 (Imploding).
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Compression Method
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Name Method Description
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----------- ------ --------------------------------------------
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Stored 0 No compression
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Shrunk 1 LZW, 8K buffer, 9-13 bits with partial clearing
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Reduced-1 2 Probalistic compression, lower 7 bits
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Reduced-2 3 Probalistic compression, lower 6 bits
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Reduced-3 4 Probalistic compression, lower 5 bits
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Reduced-4 5 Probalistic compression, lower 4 bits
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Imploded 6 2/3 Shanno-Fano trees, 4K/8K sliding dictionary
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ZOO
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---
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ZOO file header sturtures
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Master Header
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-------------
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Byte number Value(s) Meaning
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--------------------------------------------------------------
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0-19 --- Archive header text
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20-23 $A7DCFDC4 File signature
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24-27 --- pointer to 1st header
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28-31 --- pointer to 1st header - 1
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32 --- version making archive
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33 --- minimum version needed to extract
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File Header
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-----------
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Byte number Value(s) Meaning
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--------------------------------------------------------------
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0-3 $A7DCFDC4 signature
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4 --- type of directory entry
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5 0-1 Compression method
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6-9 --- position of next dir entry
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10-13 --- position of header
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14-15 --- Date
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16-17 --- Time
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18-19 --- CRC-16
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20-23 --- Uncompressed size
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24-27 --- Compressed size
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28 --- version that made this file
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29 --- minimum version needed to extract
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30 0-1 1 if file deleted from archive
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31-34 --- pointer to comment, 0 if none
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35-36 --- length of comment
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37-XX --- path/filename
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Compression Method
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NAME DESCRIPTION
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----------- --------------------------------------------
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Stored No compression used
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Crunched Packing, LZW, 4K buffer, var len (9-13 bits)
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