From Just Solve the File Format Problem
ARJ was one of the leading compression tools during the nineties. While it was a bit slower than PkZIP, it sported many more options, some of which were unique during that time (archives over multiple disks/volumes, fine-tuning of the compression algorithms used based on the data that was being compressed, recovery records to recover from simple transmission errors, etc.)
See also JAR (ARJ Software).
- Wikipedia article
- The ARJ Archive File Format, from fileformat.info
- Another, slightly more verbose, file format description (apparently moved here)