PAK is intended as a replacement for ARC by System Enhancement Associates and
PKARC and PKZip by Philip Katz. While PAK is faster than
ARC, speed is not the emphasis, and PAK does not attempt to compete with PKARC in this respect. However, PAK produces archive files that are consistently 50% to 90% of the size produced by
either ARC, PKARC, or PKZip 0.9 and supports files created by any of these
programs. While PKZip 1.0 files are roughly comparable in size to PAK files, PAK supports more archive formats and more
features.
Finally, PAK is available in a full screen edition which is much easier to use than
ARC, PKARC, or PKZip, and in a programmer's toolkit for those who want data compression in their own
programs.
PAK creates and modifies archive files, which have the
.PAK, .ARC, or .ZIP extension. An archive file may contain one, two, or any number of compressed files. Files in an archive retain all of the information they had in the directory, such as name, size, and date.
In addition, each file in an archive has a calculated CRC
number, which assures the detection of damage after events such as file transmission via
modem.