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 toc 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, and the ability to query the
table of content's rich meta-data.