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=== Deflate64, Enhanced Deflate === Deflate64, specified by PKWARE, is a proprietary variant of Deflate. It's fundamentally the same algorithm. What has changed is the increase in dictionary size from 32 KB to 64 KB, an extension of the distance codes to 16 bits so that they may address a range of 64 KB, and the length code, which is extended to [[16-bit computing|16-bit]], so that it may define lengths of three to 65,538 bytes.<ref>{{Cite web |url=http://www.binaryessence.com/dct/imp/en000225.htm |title=Binary Essence β Deflate64 |access-date=22 May 2011 |archive-url=https://web.archive.org/web/20170621195505/http://www.binaryessence.com/dct/imp/en000225.htm |archive-date=21 June 2017 |url-status=bot: unknown}}</ref> This leads to Deflate64 having a longer compression time, and potentially a slightly higher compression ratio, than Deflate.<ref>{{Cite web |url=http://www.binaryessence.com/dct/apc/en000263.htm |title=Binary Essence β "Calgary Corpus" compression comparisons |access-date=22 May 2011 |archive-url=https://web.archive.org/web/20171227131819/http://www.binaryessence.com/dct/apc/en000263.htm |archive-date=27 December 2017 |url-status=bot: unknown}}</ref> Several free and/or open source projects support Deflate64, such as [[7-Zip]],<ref>{{Cite web|url=https://sevenzip.osdn.jp/chm/cmdline/switches/method.htm|title=-m (Set compression Method) switch|website=sevenzip.osdn.jp|access-date=2023-01-21|archive-date=2022-04-09|archive-url=https://web.archive.org/web/20220409225619/https://sevenzip.osdn.jp/chm/cmdline/switches/method.htm|url-status=dead}}</ref> while others, such as [[zlib]], do not, because the procedure is proprietary,<ref>History of Lossless Data Compression Algorithms β [http://ieeeghn.org/wiki/index.php/History_of_Lossless_Data_Compression_Algorithms#DEFLATE64 Deflate64]</ref> and the performance increase over Deflate is small.<ref>zlib FAQ β [https://www.zlib.net/zlib_faq.html#faq40 Does zlib support the new "Deflate64" format introduced by PKWare?]</ref>
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