xz-utils 4.999.9beta+20091116-1 (amd64 binary) in ubuntu lucid

 XZ is the successor to the Lempel-Ziv/Markov-chain Algorithm
 compression format, which provides memory-hungry but powerful
 compression (often better than bzip2) and fast, easy decompression.
 .
 This package provides the command line tools for working with XZ
 compression, including xz, unxz, xzcat, xzgrep, and so on. They can
 also handle the older LZMA format, and if invoked via appropriate
 symlinks will emulate the behavior of the commands in the lzma
 package.
 .
 The XZ format is similar to the older LZMA format but includes some
 improvements for general use:
 .
  * 'file' magic for detecting XZ files;
  * crc64 data integrity check;
  * limited random-access reading support;
  * improved support for multithreading (not used in xz-utils);
  * support for flushing the encoder.