ARC (file format)

ARC is a lossless data compression and archival format by System Enhancement Associates (SEA). It was very popular during the early days of networked dial-up BBS. The file format and the program were both called ARC. The ARC program made obsolete the previous use of a combination of the SQ program to compress files and the LU program to create .LBR archives, by combining both compression and archiving functions into a single program. Unlike ZIP, ARC is incapable of compressing entire directory trees. The format was subject to controversy in the 1980s—an important event in debates over what would later be known as open formats.