The XAR project aims to provide an easily extensible archive format. Important
design decisions include an easily extensible XML table of contents for random
access to archived files; storing the table at the beginning of the archive to
allow for efficient handling of streamed archives; the ability to handle files
of arbitrarily large sizes; the ability to choose independent encodings for
individual files in the archive; the ability to store checksums for individual
files in both compressed and uncompressed form; the ability to query the table
of content's rich meta-data.

NOTE: This script builds a fork of the original XAR project developed by Rob
Braun at code.google.com. The forked project includes several bug fixes and
enhancements.