The XAR project aims to provide an easily extensible archive format. Import ant design decisions include an easily extensible XML table of contents for ran dom 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 fi les of arbitrarily large sizes, the ability to choose independent encodings for individual files in the archive, the ability to store checksums for individ ual files in both compressed and uncompressed form, and the ability to query the table of content’s rich meta-data.