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@@ -6,17 +6,50 @@ the one of lzip, bzip2 or gzip.
Pdlzip uses the lzip file format; the files produced by pdlzip are
(hope)fully compatible with lzip-1.4 or newer. Pdlzip is in fact a
"public domain" version of the lzip data compressor, intended for those
-who can't distribute GPL licensed Free Software.
+who can't distribute (or even use) GPL licensed Free Software.
+
+The lzip file format is designed for data sharing and long-term
+archiving, taking into account both data integrity and decoder
+availability:
+
+ * The lzip format provides very safe integrity checking and some data
+ recovery means. The lziprecover program can repair bit-flip errors
+ (one of the most common forms of data corruption) in lzip files,
+ and provides data recovery capabilities, including error-checked
+ merging of damaged copies of a file.
+
+ * The lzip format is as simple as possible (but not simpler). The
+ lzip manual provides the code of a simple decompressor along with a
+ detailed explanation of how it works, so that with the only help of
+ the lzip manual it would be possible for a digital archaeologist to
+ extract the data from a lzip file long after quantum computers
+ eventually render LZMA obsolete.
+
+ * Additionally the lzip reference implementation is copylefted, which
+ guarantees that it will remain free forever.
+
+A nice feature of the lzip format is that a corrupt byte is easier to
+repair the nearer it is from the beginning of the file. Therefore, with
+the help of lziprecover, losing an entire archive just because of a
+corrupt byte near the beginning is a thing of the past.
Pdlzip is also able to decompress legacy lzma-alone (.lzma) files.
+Lzma-alone is a very bad format. If you keep any lzma-alone files, it is
+advisable to recompress them to lzip format.
Pdlzip is written in C.
-Pdlzip includes public domain compression code from the LZMA SDK written
-by Igor Pavlov.
+Pdlzip includes public domain (de)compression code from the LZMA SDK
+(Software Development Kit) written by Igor Pavlov.
+
+I would not write non-copylefted software unless it is too simple to be
+worth copylefting it, but one of the uses of the lzip format is the
+interchange of information, and it is therefore desirable that even the
+users of the most non-free platforms can share lzip files with everybody
+else.
-Copyright (C) 2010, 2011, 2012, 2013 Antonio Diaz Diaz.
+Copyright (C) 2010-2015 Antonio Diaz Diaz.
This file is free documentation: you have unlimited permission to copy,
distribute and modify it.