Question: What the difference in formatting the disc in ISO 9660 or UDF (Universal Disc Format)? Answer: FileCD was originally designed to be compliant with ISO 9660 file system specifications, which was adopted by all Operating Systems that support CD-ROM devices. Windows 95/98/NT/2000/ME/XP, MacOS, Linux, and Unix all have "native" support of ISO 9660. FileCD has complete cross-platform compatibility: a FileCD disc can be read back in virtually all Operating Systems. NO SPECIAL READER SOFTWARE REQUIRED since the support of ISO 9660 is built-in. In FileCD 2.0 we also support formatting in UDF (Universal Disk Format). This allows users to freely exchange files from UDF formatted CD?s between other Packet-Writing software and FileCD 2.0 environments.