This tool is use to is used to detect the most common errors that can occur when dumping ROMS, for example stuck bits and address line errors. It can check the ROMs in ZIP files or subdirectories; it can also be used to compare two ROM sets, by giving it two files or subdirectories as parameters. It will determine which ROMS are identical and which are the closest matches. This is useful when figuring out if a newly dumped ROM set is a clone of another ROM set. The details below come straight from the Mame documentation. To be honest, 99.9% of Mame users will never need to use this program, but here's some details anyway.